I'm in the same boat, and have been meaning to try immich but slightly worried about migration effort. Should I import fresh into Immich or setup my existing photoprism as an external library? I think the former is probably correct, but the latter might be easier?

Anyone have experience with this? I haven't done much modification or album creation in photoprism, so am happy to start from scratch on that front.

Give it a try, Immich is truly wonderful. Rich in features, polished UX, it's now better than Google Photos.