fedora will be fine as it is the upstream provider of rpm build files

fedora -> centos stream -> RHEL

Rocky Linux and Oracle Linux that take the RHEL sources without contributing back are having their src rpm access cut.

systemd is one of the best things that has happened with linux. Instead of random shell scripts that work differently on each distro, now you have a single ini conf file for your service that configures automatic restarts, sandboxing and activation in a easy to use way.

same, its pretty solid for a meme os. For anything else I usually use Debian.