Thanks to all the people in this Home Assistant Community thread.
This code is tested for a cheap WiFi cam with software version "A9_IPC_20220506 10:41:05" and the "HB3_V0.3D210726" marking on the PCB. This Camera opens a WiFi Access Point with the "DGOA" or "DGOC" prefix and works with the HDWiFiCam Pro App.
This Camera uses the PPPP-Protocol with some sort of "propietary XOR encryption". Actual Commands to the Camera are JSON embedded in a custom Payload header in the MSG_DRW packets.
Video is received as MJPEG stream, the audio samples are ADPCM encoded.
The run.js starts a webserver on port 3000 wich serves the mjpeg data.
The run_with_audio.js additionally plays audio using the npm plugin speaker.
If you have the "DGOC" prefix, you may need to change the boradcast address: If your run.js dosent connect ('Broadcast message sent' line on screen that just repeats), use the option '-b 192.168.0.255'.
Replace the '192.168.0.' part with your own wifi ip range.