The stated intended purpose of the game porting toolkit is to enable developers to modify their games. But the software actually being shipped includes what is literally a Wine GPU backend, which is usable by (and already used and bundled by) consumer-facing Wine applications like Crossover. If you go to Codeweavers, download any Crossover for Mac from the past year (Sep. 27, 2023 according to their release notes), you're getting a tool that includes the D3D to Metal layer from Apple's Game Porting Toolkit.