I don't think that anyone other than facebook tracks (and exposes via their api) photo tagging (I hope I'm wrong, it's a cool feature everyone should support)... so this might result in filtering things based on facebook-specific data :/
Are you just looking for photos where you (or generically, the account owner) are tagged? If so, you can get that for facebook via "
https://api.singly.com/proxy/facebook/me/photos?access_token=XXX". If you're looking for where other people specifically are tagged (in your feed), you'll have to do the call you mentioned of photos_feed with participants, and then step through filtering for ones that have the entry.data.tags.data[].id that match, which shouldn't be too bad.
If there is a bigger pattern across services or this is a common thing, we'll definitely try to make it easier!