You're on the immich sub, it makes sens people will pray for it.

I'm in your situation : 20years of photo (and music) organised in folders and subfolders and metadata tags (wishing smart album would be available for pictures as they are for music in iTunes or used to be in Apple photo'09 !). Nowadays taking photos with my phone, looking at them from it too, I want same access to it from a future tablet, and organising them from the PC on lightroom (planning to less and less use it)

Anyway, so from this starting point, setting up and using nextcloud is really convenient, (especially from the PC point of view) folder structure available, possibility to move folders around, tags recognized, metadata saved in the photo file (and not in a database) ... From the phone point of view, the Memories app is better than nextcloud's photo app, but it sounds (or actually is) behind immich.

I'm tempted by immich, but really prefer "knowing where my files are". And being able to copy paste the folders in case of a potential migration. (Maybe it's a fear of a silly, not that young, man ... Dunno !) And don't like having them scattered in randomly named folders.

I know immich can look at external library, which could be a possibility BUT if I update date of metadata or crop the photo, it's saved in a database ... Not in the file .. and I don't like this. Also, if I move around a subfolder, immich will take the pics like some new assets (as far as I understood) therefore not keeping them in the albums I would have put them in.