I know that the Godot Team used to be on the lookout for someone to make a demo to showcase the possibilities of the Engine. I feel you might be interested? Perhaps check in with Remi/Juan if there's still budget?
Yes, that is what I have planned for the 4.0 release. However my last two demos have used licensed artwork and I need to be able to release the source project files. So I'll have to make my own art, but I think I have some time before 4.0 is released.