You get a link and you can set read or write permissions on it.
Whoever gets that link can browse it in a web browser.
I've used this to share albums of photos with gatherings of folks; it works very well. It does assume you have your Immich installation publicly available, however. (Not open to the public, but on a publicly accessible web server)
OK. Then you concede your security, as I can't imagine any single person self-hosting can be better at keeping their public service more secure than engineers at Google can. Especially with limited time.
How safe is that to set up for novice it people? I have a pi with pi-hole on it and am thinking about putting immich on it but the fact that it exposes itself outside my LAN frightens me.