I've also been trying (and mostly failing) to build such a setup over the last few weeks. What are you thinking in terms of the overall building blocks to get this to work?

I've been struggling to get a proper low-latency screen+audio recording going (on macos) and streaming that over WebRTC. Either the audio gets de-sync, or the streaming latency is too high.

games i plan to play don't care about latency, which solves most of your problems :)

but this+obs+a webapp for input+ydotool to pass the input to dosbox. then i can just open a page on the browser on the phone.