This would presumably let x86 windows games run on ARM hardware.
This is almost certainly meant for the next Valve VR headset, but ARM has so much better power efficiency than x86 that a future ARM based Deck would be a huge improvement to battery life.
Also see this tweet:
VR games that have already secretly pushed Android ARM builds onto the Steam Store are ran via Waydroid (androidARM to LinuxARM)
VR games that do not have an ARM build on Steam (windows x86) are being translated/emulated via ProtonARM and FEX
Edit: here’s gamingonlinux coverage of this info, includes some more information
Yep. The big question is if the gap will close enough that ARM chips indeed end up delivering better power efficiency with emulation than an AMD64 chip that delivers the same performance without emulation.
My bets would be on the native AMD64 chip ending up more power efficient. To be honest, I would not bet too much money though.