Try Universal ADB Debloater, you can probably remove most spywares from it. Surely I can’t trust it as much as a FOSS rom, but from my quick network inspection my samsung stock rom with UAD makes pretty much no network connection at all.

If I run a vpn on it then the Googled OS may still know my location(from wifi and bluethooth scanning that it may be doing nonstop)

The VPN has nothing to do with your phone’s location settings.

would the vpn only mask my activity from my internet service provider?

Yes, plus it’s a shared server so it makes it harder for websites to know your location or to track your activities across sites.

It can mask your ip from other sites, some have adblocking on them too.

I personally use PiVPN which gives me access to PiHole so I have adblocking on the go.

So like Google still gets stuff, but I figure in trying to get privacy, every little helps.

like i wrote under your last post, install netGuard as a VPN and activate “manage system apps” which will permit you to block google calling home

also, with ADB you can uninstall almost anything (be careful!)

you can also choose a dns which would block those (mullvad, for example

Worth doing, I’d also recommend looking into ADB and removing Gemini and other google apps. It’s not an ideal setup but perfect is the enemy of good

Yes. Exactly.
But why give your ISP (or any wifi you connect to) all your browsing habits?