Linux is commonly used in the communications systems, like on invidual radio "stations". Propably used everywhere where high confidentiality and security is required.

Korean war and probably Kosovo war (or Yugoslavia wars in general) for Serbia

Nope, unless you are worried about stalkers.

Real shame that GrapheneOS only supports google pixels since they are kinda expensive.

They never happened. Winners write history.

I'm not a fan of idea of completely getting cut out from parts of the fediverse because of ideological differences. Imo that just promotes further polarization. Though I might look into blocking couple instances if and when I get annoyed enough lol

I agree, and as other comment mentioned: foss seems to appeal more to the left leaning. It'll probably get more balanced with time, though not like I want more rightwing circlejerks but that the extremes would get kinda buried under the masses of sane people.

Yes, though there are some prebuilt binaries for large packages. I use gentoo on a desktop and updates don't take too long, minutes. Big updates that cause lot of packages to rebuild can take hours.

There is fine line with being tech illiterate and being able to use linux when it all just works. The problems arise only when you are just slightly more advanced and want to do something weird without actually being able do it in linux with some things being a bit too much for the average Joe.