It all "just works". No "depends_on", you just specify your "FROM" as usual and it just figures it all out for you.
You can create contexts that point to other targets. So in your Dockerfile you can use `FROM project-base` where `project-base` is whatever you specified in the context.
See "Pinning an Alpine image" here: https://docs.docker.com/build/bake/contexts/#pinning-alpine-...