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
Since Microsoft also wants x86 apps to work on their Qualcomm powered Windows laptops, can this project help Microsoft in some way?
No, not that much. The emulation of the syscalls are specific to Linux, so none of that is usable on Windows. They could reuse the emulator, but it seems likely they would write their own from scratch so they can keep everything closed source. Obligatory: fuck Microsoft.
A happy fuck Microsoft to you as well 🎩
Hey, can I join in!
Fuck you Microsoft