Kobo ebooks are the best for this, just plug them in a computer and they act as a USB key. Calibre can manage them too. Some models have a SD card slot for a lot more storage too.

I use a pocketbook since years now.

• crisp display
• eats every format you throw at it
• also bluetooth on board for listening to audiobooks or music. Means no mobile necesarry when going to the beach
• water resistant models, read in the bathtube
• send to pocketbook to receive ebooks via mail
• KOReader compatible with calibre to connect to your selfhosted server
• connection to onleihe or libby

Kobo with KOreader is a great option. KOreader can connect to your WiFi and you can rsync your library to the device.

I have a Kobo Clara which I installed (free, open source) KOReader on. I also have Calibre installed on a desktop machine with the db for that located on my server (which is in my home, not a VPS). Having the db there means it can also serve the Calibre-web install which is also on the server.

When I first set this up I used Calibre on my desktop to connect over wifi to my Kobo and pushed everything I had straight onto it in one go. Now, as I add new individual books to Calibre, I use the OPDS connection on my Kobo to connect to Calibre-web and pull the new book to my Kobo from there. This means I can access my collection wherever I am in the world.

I do have an Onyx Boox tablet, the Note 2 plus to be specific, and I do run Calibre and calibre-web on my home server.
Though I don't actually use calibre-web at all, and the full flat calibre only to organise the collection. Usually I just copy the files to my tablet manually, but I do leverage the built-in RSS reader in Calibre to create my own epub "newspaper" periodically, which is synced to the tablet by Synching.
I have also used to have (actually still have it, but not use it) an old Kobo touch with Koreader, and I intended to download the books wirelessly using the calibre-web, but honestly, I just copied it over an USB anyway...
If I think about it, I could simply sync my whole library over Synching.

I have a Kobo and use calibre to manage my books. I don't sync online it's just plug and remove what I have read and upload my next lot of books that I want to read. My Kobo currently has around 300+ books on it at the moment so I can read whatever I feel like it. Doesn't help your syncing between different devices but I guess you could us Dropbox or something like that to link up your phone, tablet etc.

I use FBReader on a couple of Android 8" tablets and my phone, it'll connect to a calibre library and stores/syncs progress on Gdrive or Dropbox (wish that was more open). But its a great reader app.

I docker calibre/calibre-web/openbooks as follows and pull my books from usenet where someone has more than likely broken the DRM. I'm just going to say, I own every book I read on paper or Kindle, I just can't stand paper books and there's no way to convince these publishing co's to send me the ebook for the physical book.

When you use this, go into the Calibre app and set up the auto-import to the Data volume that is shared by the containers. Then when you download a book, you can just press cancel to save, as the book will be autoimpored from the temp folder in Openbooks by Calibre and deleted from the Data volume.

version: "2.1"
services:
  calibre:
    image: lscr.io/linuxserver/calibre:latest
    container_name: calibre
    environment:
      - PUID=0
      - PGID=0
      - TZ=America/Denver
    security_opt:
      - seccomp=unconfined
    volumes:
      - ./data:/config
    ports:
      - 7080:8080
      - 7081:8081
    restart: unless-stopped
    labels:
      - com.centurylinklabs.watchtower.enable=true

  calibre-web:
    image: lscr.io/linuxserver/calibre-web:latest
    container_name: calibre-web
    environment:
      - PUID=0
      - PGID=0
      - TZ=America/Denver
      - DOCKER_MODS=linuxserver/mods:universal-calibre #optional
    volumes:
      - ./data/web-config:/config
      - ./data/:/books
#      - ./data/Calibre\ Library:/books
    ports:
      - 7083:8083
    restart: unless-stopped
    labels:
      - com.centurylinklabs.watchtower.enable=true

  openbooks:
    ports:
      - 7082:80
    volumes:
      - './data/:/books'
    restart: unless-stopped
    container_name: OpenBooks
#    command: --persist
    command: --name "InsertSomeAliasHere" --persist
    environment:
      - BASE_PATH=/
    image: evanbuss/openbooks:latest
    labels:
      - com.centurylinklabs.watchtower.enable=true

I'm using a combination of:

• The Boox Palma reader, though they have larger tablets if you prefer. I'm not sure about the others, but the Palma runs Android with the Play Store.
• Kavita to host my ebooks online.
• FolderSync with SFTP to sync all of my books ahead of time to my SD card.
• Moon Reader to add my Kavita server's OPDS feed as an online catalog if I need to grab something manually.
• Calibre to manage and embed metadata.

Bouncing off of this, what e-book server exists that a clients sync progress back to the server (i.e. Amazon's whispersync)?

I primarily read on one device, but occasionally I pull up my phone when I don't have my e-reader and it's really handy to have to progress always up to date.

I have a Boox tablet (an older Note3) for the actual reading, I run readarr as a downloader/manager and use Ubooquity as the server. If you arent a massive nerd I'd probably suggest a kobo reader over an android reader.

I dont tend to "stream" the books from the server, because there is no point, they are tiny files, so i use the ubooquity webui to download the file to the device when needed. though even that is unnecessary as I can just vpn into the server itself and pull the files, or have them all sync automatically when on wifi since it is just an android device so i can run whatever apps I want to do that, I just use ubooquity as I used to use its web ui reader to keep in sync between multiple devices but stopped reading on my phone as I preferred the e-ink display. could also just dump them to a usb-c disk and move them manually.

I might soon replace ubooquity alltogether and just have Readarr put the files into nextcloud or something directly and have that sync with the tablet when on wifi.

The source for the titles themselves is the usual suspects, public trackers, usenet etc.

I've used calibre in the past to convert and de-drm books for a kindle I used previously, but I never actually needed any of its other features like re-formatting or editing metadata so I stopped using it as soon as I replaced the kindle with the Boox reader.

I've owned nearly every version of the nook, and haven't had a problem getting stuff onto it.

For hosting my collection, I use https://vaemendis.net/ubooquity/ it has a built in reader that saves states, but I primarily download to my nook and read with moon reader +.

There's a docker compose and env file in https://github.com/zedd00/Boater-HAT/blob/master/docker-compose.yml that have my entire setup.

I have a 1st gen kindle paperwhite and use

https://github.com/Kareadita/Kavita & https://github.com/Kareadita/KavitaEmail

The latter allows me to configure an action in the former to email epubs to my kindle and I've been using that for the last year or so.

I have done this with calibre and a Kindle, worked fine.

Nowadays I prefer reading on my phone, and loading ePubs on any eBook reader is a non brainer.

I got a remarkable way back in grad school when it was the only real option for full size reader that could handle PDFs so I could use it to read and annotate scientific papers which don't handle conversion well. Now there's a bunch of products that can do it. But for the remarkable 1 at least, you upload books into the remarkable app and it'll auto download onto the device over wifi, so no need to plug it in. However, everything goes through the remarkable server so defeats the underlying principles of self hosting lol

Kobo devices are easy to install KOReader on.

You should also ask yourself what kind of books you want to read. Black and white comic books, for instance, can be read on an e-reader, as long as the screen is big enough.