Home servers are the best, but I have very slow upload and there are security risks with this if you don't isolate the server properly.

Yeah it would work, but home internet bandwidth is the bigger concern here. I don't unfortunately can't estimate a user count.

If you are a student you can get DigitalOcean free $200 and Azure free $100 through GitHub student dev pack.

Well in theory yes but no federation.

Why would you not want to run it in docker compose?

Yes if you are in a country that actually cares about you torrenting stuff (ex: USA). Generally a simple WireGuard instance will do the job very well.