Does anyone know if it’s possible to achieve this? Possibly with an external service that syncs the two?
Basically, the last feature immich can’t do that google does is to share albums. Sometimes my family wants to have albums after events, and my ones live in a silo.
Afaik immich is generally safe to publicly expose. Otherwise, I’d just use http basic auth. Supported by every server and client, should be secure enough to hold off attacks in case immich’s login/auth mechanisms fail, and I don’t see a usecase where this wouldn’t work.
If you don’t have a public IP or need IPv4, get a 4€/Month VPS (cheaper than even a Pi’s energy usage I suppose) and put headscale on it.