Removing by ADB is fine if you are able to identify which packages should be removed or if they're already covered by Universal Debloater. You should also use Invizible Pro to control what connections are made and block trackers.

It's unclear to me how these torrents are used. If individual books are not downloaded from them, is this only to make it possible to create similar sites in the future, in case this one is taken down?

Gboard isn't open source, which is why I disable internet access for it.

I use Gboard but with internet access disabled for it. I haven't found a comparable open source keyboard yet.

That's pretty cool. I might have to set it up this weekend.

What's the use case?

Would "plus" addressing work for you? https://proton.me/support/creating-aliases

Remove Google apps as part of the debloat process, restrict permissions beyond what Android allows by default for all system apps, using App Ops and Shizuku. Accomplishes the same thing as GrapheneOS.

You can make stock Android much more private. Universal debloat tool + Invisible Pro - remove unnecessary apps, restrict internet access to only the apps you want to have internet access, add a tracker blocker list.

My experience has been that Nextcloud can do 1000 different things, and it sucks at all of them.

Where's the memmy Android download?

Maybe open a dispute with your bank