private as possible

What are you trying to hide, and who are you hiding it from?

I dislike that some privacy forums, like reddit and therefore here by proxy, have a cultural habit of talking about privacy or security as an abstract value in itself. But when we start getting into more detailed questions, it's all vague and vibes until we make it clear who we're trying to hide from and what we're hiding.

For example, most of the time I'm not hiding from my own government. Sure, I incidentally do make it a bit harder for them to track me, but I'm more focused on hiding from Meta/Alphabet/Amazon/etc. (plus from a small group of deranged online stalkers obsessed with some of my friends) so there are plenty of online services and stores I can buy from without taking inconvenient measures. It's fine for me if some services can guess my name and know where I live and one of my phone numbers. It's not fine if they learn some other details.

It's important to get out of the habit of saying "more private", "less private", "most secure", and talk about what your specifically concerned with and how tactics and tools specifically address that. What information will Google gain from knowing your investments? Is that a threat to you? Are there acceptable ways to mitigate that threat?

Using google to create an account would mean giving them my real data

I've been surprised how easy it was for me to make a fake Google account with no links to my real identity. I only use it for age-restricted YouTube videos, I wouldn't trust it with money like investments, because the way I set it up is inherently suspicious and I wouldn't be able to verify identity if challenged.

No.

Not because it's not technically feasible but rather I would psychologically not manage to make money knowing my portfolio, either directly or via EFTs, makes me money by profiteering of BigTech or surveillance capitalism.

Full disclosure : I did have Apple and NVIDIA stocks and I did sell them not because they were not making money (there sure were) but because I felt disgusted by HOW they made money.

PS: KYC and related laws in a lot of countries demand you use your real information and declare your earnings, so again it's not a technical problem, it's at least ALSO a legal problem, and arguably a moral one if you believe KYC kind of laws help to curb money laundering.

I like my privacy and all that, but I would never let it get in the way of investing. When you're old, broke, on the verge of being homeless, eating low-grade ramen noodles for every meal, are you going to say "At least I kept my privacy intact!"? F--- that.

As with any business/industry, if a company limits you to a certain platform (like phone apps), find a different company. There are plenty of competitors out there.

Personally, I would go the S&P 500 mutual fund route. It's too easy, and it beats most other investments out there. But if you're determined to go the DIY route, you do you.

TL/DR: I do everything on my desktop. I can check my accounts from my phone, but it's not required for anything.

I keep separate devices and networks. It is not privacy as much as it is purging suggestive content and convenience. I only purchase something when I go looking for it specifically. I never browse or shop as entertainment or for endorphins. Investment apps are all about the stalkerware because it says you are a major target for unnecessary nonsense. Get a tablet and only use it for that junk.

invest engine or vanguard:

you can just use the website, dont need the app!

The fact that you're still using Android 8 makes everything else moot, seeing as it hasn't received a security update in nearly 5 years. I would take care of that before anything else.

Any legitimate broker is definitely going to have a desktop site, though.

I would consider Fidelity or Interactive Brokers.

If you are in the US, take a look at Fidelity or Vanguard. They haven't required the use of a smartphone app.

Using a phone with Android 8 isn't best practice for security by any means, but unless you are being targeted or going around downloading shady apps, it's more likely it will run into app incompatibility issues in the coming years than anything else.

For sites where I'm making a low-value, one-off purchase and never coming back, I'll use a pseudonym alongside a prepaid gift card, or failing that, a privacy.com virtual card. Not quite a sustainable strategy with eBay or Amazon, especially if the package needs a signature, so I'll just use a privacy.com virtual card and supply a P.O. Box address

Mostly accepted that it is the way it is for these things. If the privacy-friendly option is giving up a few conveniences, I'll take it. But if it's keeping me from reaching certain goals, I'll tolerate a compromise. I don't think I'm being targeted either, so it's all tolerable in my personal threat model.

Buy monero. No need for all that pii

I've learned that it all starts with the phone, and the internet router. The phone is essentially a little computer that people use as a wallet. Phone number is connected to almost everything people do. If someone has a smartphone they should update it every 5-8 years, even if they don't use online banking.

Personally, if I didn't want to buy a smartphone I'd just get a fliphone. Those are like $15, $20. You can afford to buy one of those every 8 years. Tracfone sim cards are essentially disposable so it's possible to use a phone number to create an account and then discard it if needed, or keep it active indefinitely. When I used Tracfone, I'd pay by the minute or by the text, and the time would last until used. I'd pay $20 once and get say 60 minutes of talk and however many texts. At the time I communicated mostly on messaging apps so I'd use the phone number for things I'd need a phone number for, like the doctor. The smartphones are like $40-$100.

I wouldn't use fake identities for e-commerce but rather I'd choose a trusted e-commerce platform, use a fake email and phone number because they now demand both but use your real name and address. I don't know how you're getting things on e-commerce using an alias, because they need to be able to send you the thing you bought. There's a service called Hushed, requires a tablet or phone, which sells phone numbers in packs of 1-3. 3 pack of phone numbers is $15, so you could have a phone number for personal use, a phone number for work, a phone number for e-commerce. There's also MySudo, which sells 9 pack of email/phone number aliases for $15. With Hushed it's possible to login on other devices but MySudo is device encrypted and requires a QR code to sync a limted number of devices.

If you're interested in investing, want to use a mobile device for some reason but don't want a phone, you should get a fliphone and a tablet instead of using a smartphone. A lot of smartphone apps, including those for online banking or trading, are also on the tablet. Tablets are a lot more advanced today than 5 years ago, and they're more like 'lite' computers, but they have the same smartphone apps a lot of the time. But, you'd have to feel comfortable spending $200-$800 every 8 years on a tablet instead of a phone.