In addition to Supabase Auth the sibling mentions (which I played with very briefly) I've been using clerk.dev (no affiliation) and it's great. Depending on your definition of doing it yourself it could be just want you want. You have to set some things up, you're not going to get things like row-level permissions you get out of the box w/ Supabase, but if you're looking for a quick implementation where things like password reset etc. are handled for you, it might be a good fit.

I've been using Supabase for authentication/authorization in my recent side project.

The main app is node/express running on Digital Ocean and it connects to directly to the Supabase hosted Postgres for most operations, but then uses the Supabase auth API for auth related stuff.

Saves a lot of time sending password reset emails etc and the entire project costs less than $5/mo in hosting costs.

Would you consider a project like https://github.com/authcompanion/authcompanion2 for the authentication side? Missing anything?

I like https://github.com/goauthentik It has Helm charts and a Terraform provider.