Can realtime subscribers be hosted server side?

[kob490]

I'm new to Supabase and am looking at a Realtime (pub/sub) with fan-out solution. I wonder though if subscribers can be ran from within a function and if not, how could I host and run them 100% server side? in Vercel for example, it seem that functions do no support subscriptions to data events, and I wonder how this could be handled in Supabase?