With the caveat that I haven't used Wayland ... [1]

Waypipe is supposed to help replace things like remote X. I'd be surprised if there's no vnc server that offers a wayland desktop... that would be a big missed opportunity.

For your noisemaker, I think you might have a better time integrating at another level. Either intercept the inputs before the display server gets them, or integrate into the display server itself. X was more flexible, but as long as it's just typing -> noise, you don't need it to have the same architecture as it did in X.

[1] Wayland has no compelling features for me, and X remains viable for me as well. At some point, hardware support might be compelling, or IMHO, something will come to replace Wayland and X that is compelling.