Its my second approach (after a long break). This time not as Ofelia bindings (that should be possible too), but as a implementation for Open Frameworks. But with ofxPd its also usable with Pure Data (thats what I want it for)...
https://github.com/Jonathhhan/Pure-Data-Ofelia-Emscripten/tree/main/webMidiExample
https://webmidiexample.handmadeproductions.de/