what NAS should I buy?

[ed]

Yes, both Synology and Qnap will allow you to organise files into folders. You can then switch from folder view to other filters such as face recognition or GEO. Qnap will allow additional functions such as object recognition. If you do not want to keep your app open to synchronise your photos, WD NAS will allow that. They do not have a face recognition option, but otherwise, they do a good job with seamless backups.

I hope this helps.

https://www.synology.com/en-global/DSM70/SynologyPhotos