I have a Samsung Galaxy J3 (2018) smartphone which currently has the stock Samsung Android OS installed on it. I wanted to install an Android "distro" that doesn't spy on me, like Graphene OS, but I couldn't find a ROM for it. Since I would probably need to compile AOSP from source code anyways, I though, why not install Gentoo on my smartphone (doing the compilation on a more powerful computer using distcc). I have already installed Gentoo on both my laptop and desktop from a stage3 tarball and I'm loving it, so I guess doing the same on my smartphone wouldn't be too hard.
Now, the problem is that I need to use a few apps that are not available on Linux, like the proprietary app that I use to pay for my bus tickets. How well does waydroid work?
Ok I'd cut through all of this and focus on your needs: phone with no spying, can't find rom.
I assume you mean your phone isn't supported for graphene, lineage, or calyxos, or any others I missed?
Easiest way: buy a phone that is supported for the privacy minded os you want.