And essentially Steam is already doing exactly this, with no of this NFT non-sense. CS:GO skins are unique(if not duplicated by Steam), transferable items, with possibly their own patterns, wear patterns and even customizations that is stickers, which themselves can be modified. And people even trade and sell these on Steam...
This has been touted for years now.
It's not something studios are going to want to support, nor code for - how does this item behave in an entirely different game by an entirely different publishing house? Do I have to write my game to support every single possible one of these? Why would I let you bring your level 9000 sword of whacking into a new game?
And steam can already easily make something unique - they are the authority there, there's no need for trustlessness.
(edit - you know what? Proof of ownership is not the hard part of transferring assets between games, it's likely to be pretty darned easy to do that just with a database. Textures, models, in-game attributes, all that stuff. That's the hard problem there, if anyone even wants to bother.)