That's interesting! Does it work for streaming video or just audio? Sometimes I'd love to AirPlay from my video editing software to my iPhone to check how it looks on the smaller screen, checking colors and overall appearance.
We’ve been looking for something like this for our conference room. A PC presenting on a large TV, but mirrored/AirPlayed on iPads for anyone that wanted a version closer to their face.
You can give this a go. Made it for just this type of scenarios: https://bluescreen.live
If it works for you, happy the help you setup a private instance or something. And for in-office use, maybe optimize for quality rather than minimal updates it is now.
Sunshine and moonlight are what you need.