I've been using Hydrus [1] for the longest time now. It covers all of my tagging needs. Using the API, I can tag images using AI models [2], and have a client [3] to search through files on my phone. Native features also include automatic imports, backups, deduping, and much more.

The maintainer is working tirelessly and pushes new updates every week. It's one of the most underrated pieces of software ever, in my opinion.

[1] https://github.com/hydrusnetwork/hydrus

[2] https://github.com/Garbevoir/wd-e621-hydrus-tagger (monkey patchable to use other models besides anime ones)

[3] https://github.com/floogulinc/hydrus-web