Hello @CaptainCoward, Steam can't know what game binaries can be run as a Linux native alternative without the game dev(s) configuring their game to run with them in the first place.
A third party Steam Play compatibility tool where the community can maintain a table of matching games to their alternative implementations would be a better place for this.
Nothing extracted yet.
I know there might be hardly any use for this. But it shouldn't be too hard to implement. The reason why i mention this is the game Unreal Tournament. You can run the Steam (Windows) Version natively on Linux by applying some patches. Though when doing that it seems like steam is using the global set compatibility mode - although not needed anymore. It would be great if instead you could just select "do nothing".