For UI you would want to use a image of your character, BB doesn't lit up 3D in UI. The Shop works with any amount of levels, make sure you configured Store Group and IDs correctly.
I actually export your SPSS BBDOC to Buildbox world, it crashed then I exported it from Xcode to my phone it also crashed. I sent a video don't know if you can see it.
it seems to me the reason the game is crashing Everytime I tried to purchase something was because there was no store Identifier but I’m not sure though.
And I’m tryna add a fire button in my game UI, when the game starts I want the button to have an amount of bullets once used, the player will need to refill or buy from the shop system. Would that be possible for you to make that happen?