I think something like Twitter hinges on people/organisations being there that are popular for whatever reason. Many people engage with those people’s posts and react to each other. Since there aren’t many such people on Mastodon, there isn’t as much activity.

I recommend void. It’s rock solid, “stable rolling release”, no systemd, amazing package manager. The installation is a bit more “advanced”, but I guess coming from Arch that should not be a problem for you.