Shadow: Rent a beasty machine accessible from anywere
shadow.tech
shadow.tech
Downsides were that it became much pricier over time, there was a long waitlist to get access to it, and I did have some trouble getting my xbox controllers to work consistently with it from a Mac host. (Some of those may be worked out now.)
I think in general its an excellent solution to a problem most people don't have. It didn't really outperform stadia or Nvidia GFN by a wide enough margin, and the only real advantage was having the whole of a windows box to work with when you needed it (I never did, and probably would have used a virtual machine if I did.)
If you have a specific use and requirement you'll pretty much need to try a streaming game service and see how it goes. There are several of them these days and they often have free trials so it's not too ridiculous to just sign up with one and see.
Tl;dr 2-3 NVIDIA Quadros split up over hypervisor