Can I run Prefect fully on-premise without cloud features whatsoever?

Yes see Prefect Server which is Cloud but self-hosted. But note that we are SOC2 compliant and we also run on the hybrid model so we don’t see your data or code to begin with. Cloud definitely has features that makes things easier like Secrets, Automations, etc.

yes - you can host everything internally

Yes we do have people self-hosting as well

What do you mean "Cloud but self-hosted"?

Nearly identical to Prefect Cloud*, just a bunch of services not included