ive approached the same thing but slightly differently. i can run it on consumer hardware for vastly cheaper than the cloud and don't have to worry about image sizes at all. (bare metal is 'faster') offering 20,000 minutes of transcription for free up to the rate limit (1 Request Every 5 Seconds)
I contributed "whisperfile" as a result of this work:
* https://github.com/Mozilla-Ocho/llamafile/tree/main/whisper....
* https://github.com/cjpais/whisperfile
if you ever want to chat about making transcription virtually free or so cheap for everyone let me know. I've been working on various projects related to it for a while. including open source/cross-platform superwhisper alternative https://handy.computer