Floorp is kinda sketchy these days, it went closed source, then maybe reopen sourced. I would say Zen is the better pick. and on Android Fennec is a great Privacy fork of Firefox.

#ebooks channel on irchighway afaik

I remember at some point there was a good IRC channel for this too

I would argue FOSS is more akin to cooperative anarchism or library economics. Murray Bookchin

Brave browser is on the list and is an American company. Why not LibreWolf and Zen Browser as good Firefox forks.