I'm not sure how many people might be interested in this, but I was rummaging around trying to see how best to get around the lack of a catalog/DAM feature in Affinity. Apparently such as feature is coming, but so far no news of when, just news that we'll have news sometime this year. Sadly that's not clear that we'll actually have the new feature this year.
Anyway, the Photoapps website, which once specialised in Aperture, has news of a small app that makes Photos work better with Affinity or any other program as an external editor, using Photos as a catalog hub.
https://photoapps.expert/tips/2016/4/6/external-editors-photos-affinity-and-beyond#.VyBQNWOaeSM