Yes. Valve has done a ton of work here because it's required to be able to run x86 games on a Steam Frame which has an ARM cpu.
As sibling pointed out, the Steamdeck basically runs a Ryzen 3 7335U which is x86.
The Steam Deck is pure x86, it's not an ARM-based CPU. The Steam Frame might be what you're thinking of.
Steam deck runs a full x86-64 AMD APU. The work valve has done for that was to get Windows games to run seamlessly on Linux.
Hopefully in 2026 the Valve Index VR headset which is ARM (Qualcomm?) we get what you're talking about here - basically proton for Win32/64 to Linux ARM64.
Side note that Windows on ARM isn't bad just that its priced out of its league and cooling is awful for gaming on current laptops. The only issue I had was OpenGL needing some obscure GL on DirectX thing for Maya3D to get games to work.