Of course there is, as soon as MM is based on Godot 4. And it's not very complicated I guess, just waiting for Godot. ;)
Was that whole thing just a lead up to En attendant Godot joke?
Nice. Very nice :D
Also happy to hear, since glTF is going to be super important for my workflow, and I really like using material maker!
Please don't hesitate to contact me on discord so I understand what you need exactly. Maybe I can do something before migrating to Godot 4 (I absolutely don't know when it will happen), and this could help me anticipate future glTF related features.