OpenAI has a transcription AI (https://platform.openai.com/docs/api-reference/audio/create).
I've not tested it, but it could make for a very nice experience.
Of course, there is a cost for using their API, so there would have to be some kind of in-app-purchases situation to pay for the use. THat in turn would mean that the app could no longer be open-source.
I think I would probably need to do a whisper-backed version of this as a separate product, maybe "Captain's Log"?