The Xbox One has an NT kernel and DirectX as the graphics API. Stadia's use of Linux and Vulkan are probably about as helpful for a port to desktop Linux as an Xbox One game is for a Windows port.
That analogy is the biggest thing to happen for Linux porting since Valve's Proton SDK - all future MS-funded Xbox One games do come to Windows (albeit as UWPs) and run great.
I think "MS-funded" is doing a lot more of the work there than the kernel and graphics API are.