A New tag may not be a solution because It needs adoption and May be flooded again with bad quality.

But, here is an Idea:

Create an interface like steemfollowers.com, but to join and to be listed the app the user needs your approval, wich would happen after some manual check of the quality (or maybe a community vote).

Now you create a New tag related to the app.

The feed of the app would only show the posts by the approved participants that contains the newly created tag.

That way, you have a personalized filter, and the participants would also see through the filters and vote on the best photos.

It would be kind of a closed curation community.

Maybe hard to implement, but doable.