I checked out your store and I have no idea why would you do not use same registration as in game. You have my Steam ID, and XBOX.
If I buy from the store now, you have no idea if it is a player with 2000 hours in game or his brother with 5 hours.
I would also enjoy if I buy like a t-shirt and got for example 5 dublons in game.
In Valve store I can log in with Steam and it makes sense to buy under my account bc I get virtual stuff. I am not saying to copycat, but to make it connected and more interesting for players.