I’d also highly recommend the proper PC, Immich can get pretty RAM-hungry if you use the ML functions, for me that has actually caused crashes before. Granted, that was while importing roughly 20k Assets (200GB) from a Google photos takeout, but it’s still probably better to be prepared.
To be fair though, those warnings are not really representative of the current user experience. I’ve had Immich running for about 6 months by now, and apart from the very frequent updates the only annoyance was when they recently changed their database scheme, and I had to manually add two extensions to my Postgres. Everything else has been rock solid, and has been improving at a massive pace
I’d recommend I’m mich instead of Photoprism, at least for this usecase. I have both running, but I use Photoprism primarily to organize and share pictures taken with my SLR, while Immich handles Automatic Backups and sorting of all the pictures I take with my phone. Additionally Immich has way better (and still offline) facial detection, it’s almost scary how good it is sometimes