I have minor beef with Immich and basically any larger project and the way they go about their Docker Compose. Basically I feel they make the assumption that they’re the only thing running.
^Disclaimer: I fully accept this is all just me being too stupid and not the Immich development team.
This might be my turn to be too stupid but isn't the point of docker that they all run in containers so it doesn't matter? They can all use the same database port, because the database is in a container and so doesn't prevent another database container using the same port. The port doesn't need to be exposed to the host.
The only issue that comes up when running lots of services is accessing them all over http, and that's what a reverse proxy is for. I run a dozen services on the same machine, mostly using the default docker compose files, and never have to mess with things like you have here.