Where's the decentralised part there? A game maker can already add a row to their database saying your account owns the item with a lot less overhead. You already have to rely on the game maker anyway to allow you to use it in the game, whether it's a row in a table, a digitally signed message, an NFT or a paper certificate.
NFTs would add lots of complexity to the cases you mentioned, but I don't see that they're bringing any value other than buzzword compliance.