Anyone know if it's possible to create a procedure that's only callable with the service role?

You should be able to, but I haven’t tested this personally as yet. When I get back at my computer I will check.

Awesome, thank you!

You can do that using schemas, just check what auth.users table is actually under and use that schema too for your function. Something like Create or replace function myschema.my_function_name()

ahh, nice! great idea

Be careful of adding tables and functions

Definitely, but its completely fine if using service role token which is what its meant for :)

These are schemas created by the Supabase team and could be modified in the future for upgrade purposes

How would you recommend that then? Creating new schema and grant it superuser?

Yes, but do note that the role of super user is being recommended against in the latest Postgres if I remember correctly