I built one and use it daily myself, it uses Whisper for local transcription and Llama 3.2 for local AI conversation, it has good UX as well, support live record or importing any audio/video files.
I use it for transcribing meetings, youtube videos and then dump the transcription to ChatGPT for summarizes. Recently Notion launched Q&A feature, so searching for answers in my past meetings and TLDW youtube videos is just easy.
https://apps.apple.com/us/app/notes-ai/id6477414161