>>309691471]
HTC has the Vive Focus and there's the Pico Neo 2 as well, but both are enterprise only. Lenovo used to have the Mirage Solo that was a standalone Google Daydream headset, but I'm pretty sure it died even before Google killed Daydream.
I don't see any chance of a standalone headset that just runs Steam versions of games though, and I think it'd be hard for most headset makers to get the kind of library that Oculus has.