Well, I sometimes quickly code with Tynker to test some code ideas, if I can’t be bothered using a PC.
The app “Pocket Code” for Android is free and lets users use their own pics and publish their games to a website for others to play. I think comments are allowed below a projects screen as well.
Pocket code has more types of code blocks than Tynker,Hopscotch and Scratch.
My cheap android mobile is too small and weak to use Pocket Code in any enjoyable sense.
Other than Tynker, you don’t really have any competition on IOS, as far as using Scratch type blocks to code with.
I think $3 a month subscription to let users upload their own pics would be popular. Courses that teach to code could be a separate in app purchase for users who want it.
An idea I mentioned long ago was to have advertisements play before a project starts. This could be only in the free version of Hopscotch. You have data showing the average amount of projects played per month on your servers. So you should be able to calculate how much money would be coming in if a 15 sec advert plays before a project starts. You would have to remove the ability to save projects that aren’t the users own, to ensure adverts are played each time a project starts.