Me neither. I only (have to) use Windows at work, all my own PCs have been running Linux for decades…

I do know however, that WSL emulates most (but not all) Linux syscalls, so you can ran (nearly) all Linux programs on Windows - including WINE. There is also a driver in Mesa so that you can render 3D graphics from within WSL on any DX12 graphics card.

They will likely write their own emulator, but don’t forget about WSL. You can already run WINE on Windows, I wouldn’t be surprised if you could also run FEX+WINE on Windows for ARM.

by intercepting syscalls and executing them directly

Not only syscalls. FEX and Box64 also allow using native libraries instead of emulating them. That leaves basically only the game logic to be emulated.

ARM based Deck would be a huge improvement to battery life. Don’t get your hopes up too high. You will need an emulation layer like FEX of Box64, and unlike WINE those do have quite a substantial overhead.

It is impressive how far those emulators have come, especially since they got the option to use native libraries instead of emulated ones, but the game logic itself will always need emulation…

This doesn’t mean it can’t be done, it just means that the ARM CPU needs to be pretty fast to counter the emulation overhead, and that’s why I have my doubts about the energy efficiency…

(Btw: I have tried running several AMD64 games on my A311D powered MNT Reform laptop with Box64. It’s impressive how well the emulation runs, and how many games are actually playable already. However, I also encountered a lot of games that don’t reach enjoyable FPS on that hardware. With a faster ARM chip though…)

I would rather trust GamingOnLinux here:

While it is not in any way officially supported by Valve, they have now released Windows drivers for the newer Steam Deck OLED model.

(emphasis mine)