I had no clue Chrome already used Openscreen Protocol! I thought it was just an in-progress idea & that their casting ecosystem was all something different. https://github.com/w3c/openscreenprotocol

It's lamentable that so far this very cool part of the web has no open interoperable solutions. I'm so delighted to see this hackery & hear it works!! I really really really hope it sticks, until a real answer is provided.