I implore you to join the keycap designers discord if you really want to design sets. Firstly, GMK will not run this because it uses intellectual property, and your title shows that you haven't even considered that. Furthermore, I don't think this concept could hit MOQ naturally (by that I mean without vendors practically buying out the set).
If you really want a Minecraft themed set, ditch the Steve face and try to find things in game that you think would make for a cool themed set. No faces, just basic colors to begin with. Eventually you could do novelties, but as I said, GMK is very strict as of late about using IP. Again, the keycap designers discord would show you the ropes, but there's a lot that goes into making a keycap set that I don't think you are considering at this time.
