Immich is more of a personal camera roll app, modeled after Google Photos. You can make albums and share them publicly but it wasn’t meant as a public photo gallery.
It can work if the emphasis is on self-organization but it’s quite limited due to the fact it insists on merging everything into a single photo stream and forces you to use its albums to split it back up again.
There’s no way unfortunately to have multiple photo streams per user (unless you’re willing to juggle multiple user accounts).