Linux

Shiftbook 2 https://shop.shiftphones.com/shiftbook-2.html

It's not without some flaws (much of which really doesn't bother me and I low-key find them as a feature), I really love this jank Chinese 2 in 1 I picked up. P8 mini laptop. I will say there are alternatives that have a better non swiveling screen... I would go for one of those as I feel like it's going to be problematic long-term

Also consider Lenovo Duet Chromebook 2-in1s. They're not fast, but are a good balance of Linux and Android, and very affordable.

A Surface Go 1 has been my daily driver for the last 4 years on Fedora.

I’m mostly using it docked to a USB-C screen but it works fine by itself. I’m also using a keyboard so it’s mostly a PC and not a tablet anymore😅

But I’m really happy with it and it works almost flawlessly.

Starlabels starlite tablet looks really nice. I actually just ordered one the other day. I don't have it yet so I can't give you a review but from what I have read it's pretty nice. It's an Intel machine, upgradable, running coreboot so the compatibility should be high.

Why not a PineTab though? It is the exact thing that you're describing.

Xiaomi Pad 6 is a good price and is compatible with plenty of custom roms. Some people don't trust them because it's a Chinese brand, but I figure the odds are about the same that it's got hardware level spying as a Google or Microsoft tablet. At least it's easy to root or reformat.

The Minisforum tablet seems to work well with Linux.

Tablet linux is not perfect yet, I'd suggest a pixel tablet w/ custom roms unless you are willing to use a slightly buggy linux interface. If you are willing to, look at dell latitude tablets or surfaces

I'm guessing ARM specifically? I use a Lenovo Yoga convertible in tablet mode with Fedora and the onscreen keyboard for media consumption, but not as my daily device. Not great battery life, but I got it dirt cheap used.

Do you absolutely require linux? If so something like a older microsoft surface would be best probably. Where its a full computer x86 based and has a detatchable keyboard, or a 2-in-1 that folds the keyboard back. Downside with this is worse battery life, and itll be a bit bulkier.

If what you want is just a tablet that does not spy on you id actually reccomend just getting a pixel tablet and putting graphene OS on it. Its a custom android ROM that strips a lot out and sandboxes things to give you more control over the device while still being based on android and bringing the advantages that has (battery life, mobile optimization, etc). Down side is you dont get the full Linux OS youd want.