I wanted to buy Grounded mine on Instant Gaming. But since there are no game codes for the game on Instant Gaming as the Steam version, I can't do that. However, there are game codes for the Xbox One and now I'm wondering, since Xbox One and the Microsoft Store are basically the same, whether you can also use the code in the Microsoft Store, because the game is also available there.
The stores are basically identical. But not every game supports crossplay.