I have a homelab setup with my media server stuff and frigate (for security cameras), and they're only accessible via tailscale if I'm not at home. It would theoretically be easy enough to throw immich in there as well but I don't know how the app will behave when it can't reach the server half the time
Immich has automatic URL switching, so it detects which network it's on and select between the internal and external URLs. When I'm not on my home WiFi it switches to the Tailscale URL. Tailscale must be connected for this to work obviously.