SpiceDB is an open source, Google Zanzibar-inspired, database system for creating and managing security-critical application permissions.

SpiceDB

A RBAC with resource granularity.

Example: 
In my App I have the:
- Resources: organization, etc
- Roles: org_owner, org_delivery, etc

So, a user will have one of the above roles/permission over one or more resources, not over the App (all resources in the App).

User1:
- org_owner of organization1
- org_delivery of organization2

User2:
- org_owner of organization2
- org_delivery of organization1

The point is, I don't have a lot of users, spicedb with all that infrastructure/services seems to be too much.

And I don't want to build an authorization system, it's a trivial problem ... 😅

you'll need to run it and some form of datastore (MySQL, Postgres, etc)

the easiest way to do so is the SpiceDB Operator if you're on Kubernetes

All these services there: https://authzed.com/docs/spicedb/feature-overview#architecture run at the same container? I was thinking each one was a container in the SpiceDB stack.