I just noticed an uptick in responses when a post was put up regarding coloring which is a big thing right now. Coloring apps are a great stress reliever and can be supported entirely by advertising and can promote the artrage flagship package OR you can offer color plug in packages for sale to the group on a trial to see if there is any interest.

There is precedent.

Medibang Pro which is a free Japanese applications and is as good as Paint Tool Sai or Made with Mischief and in some instances even Photoshop offers these free variants so if you want to see how it is done you can take a look. Might be worth your while. You already have the engine--just need to cobble the rest together. Thanks!