not GP (hoping he responds tho) but i've been collecting a couple of diarization options: https://github.com/sw-yx/ai-notes/blob/main/AUDIO.md

basically whisper.cpp has some support but its not great (based on my own testing)

- https://huggingface.co/spaces/vumichien/whisper-speaker-diar...

- https://github.com/Majdoddin/nlp pyannote diarization

- whisperX with diarization https://twitter.com/maxhbain/status/1619698716914622466 https://github.com/m-bain/whisperX