pretty much, both Debian and Red hat have tons of child operating systems, to coin a new termIf you learn how to use a Debian, RPM and Arch based systems you will have covered most of them.
here's a large portion of them:
in terms of which systems are actually get updated, and which ones are practical to use [for you], the list is much, much narrower. I installed FreeBSD on OracleVM about a year ago, and it appears that it's only useful on some organization's network, which makes sense since linux was basically a Bell Lab's creation.
What I lament is the fact that there aren't very many functional smartphone systems which are not proprietary. There were some you tube videos that i thought sounded kinda paranoid about the tracking nature of smartphones (one guy said google, with a straight face, was an "evil actor"), but i do think the shadowy zero-control nature of smartphone software should be a huge concern for all consumers...