Falken

The specific distro doesn’t really matter. What matters is package choice (being able to do the few things you listed with the apps you would like to use). I guess if you’re among the Debian evangelists you probably value stability more than any other consideration. Just pick some server distro or Debian again.

Even if your security oriented it seems many frown upon any self hosting whatsoever.

I got a small team in school to all adopt my self hosted Matrix as a chat solution for a project we were working on throughout the year. It was great. Everyone jumped back to Discord after we graduated though.