The Steam Frame probably has to be an ARM processor, because you don’t want to have to wonder about space and price constraints with an x86-64, and whether an eyeball makes a good heat sink.
And it probably doesn’t matter much, but that’s one less thing to worry about when porting from the Oculus Quest.
But unlike Proton’s Faustian bargain (the catalog all works! …why port at all?), in VR, the user tends to convert low framerate into vomit, so a real native port could be _crucial_.