If i'm not mistaken, Apple doesn't even have a "separate wallet" requirement like Consoles do where, if you have a cross-platform game with virtual currency, you have to keep currency purchases made on one platform separate from currency purchases made on competitor's platform - Eg. in Fortnite, purchasing $10 of VBucks on the Nintendo Switch means you have to spend those VBucks in the in-game store while on the Switch, you can't go to your PC and spend them or combine them with VBucks you've purchased from Epic directly.