I get to give you access to all my photos so that you can just proxy calls to my server?
This is a self-hosted app... The only person who has access to your photos is you - that's the entire point of using this. It lets you share photos/videos/albums from Immich without giving anyone access to any part of your Immich server, thus significantly increasing your privacy and security.
It doesn't forward any traffic to Immich, it creates essentially a WAF between the public and Immich. It validates all incoming requests and answers only valid requests, without needing privileged access to Immich.
Put it on a different server then. It prevents your Immich server from ever needing to be exposed publicly. That's the entire point.
You seem to understand neither security nor privacy.