I don’t think I’m interested in an NVIDIA Shield since if I like the idea of running any Linux app in case I want to use it for another purpose in the future.

An RPi could be a choice. I forgot that the 5s have hardware decoding. Assuming the 4GB model is suitable, then $60 + cost of a case isn’t too bad. I assume the hardware decoding could keep up with 4k60?

No, I just was under the impression that Moonlight was the best solution

Not anymore. They are owned by Songtradr now