FOS: Stands for "Free Operating System" as an inclusive term. Includes GNU/Linux, NonGNU/Linux, *BSD that are meant to liberate ones computing.
I'll start, I use Linux Mint on my laptop that I use for work daily. It uses the latest Xanmod linux kernel and flatpaks for apps with GNU Guix providing everything else.
It took me a little over a day and a half to get a base install (no desktop environment or anything) on an old netbook w/ a Pentium U5400, and this was back before binary packages existed for things like Firefox. I don't want to imagine how long it would take to compile WebKit, Firefox, and all of GNOME on that. I've since upgraded a decent amount to a slightly newer Thinkpad, so things might go more smoothly this time around when I get around to trying it.
Wild. I always used to get a minimal system with tmux or whatever and some simple stuff like that going so I could use the system while the rest of it compiled.