Check out Talon Voice. It’s a bit of getting your head around, but I use it for not just transcribing, but also coding, and general computer navigation.

Sayboard on fdroid is an option as well https://f-droid.org/packages/com.elishaazaria.sayboard/

The offline AI that I tried a few months ago probably needed training on the noise environment to get decent results. I forget which ones I tried but likely the ones with extensions already in Oobabooga Textgen. I was messing with text to speech mostly, but some of the ones that do TTS also have packages and examples for STT. Nothing I tried for offline generation was good enough to speak as an AI prompt without manual corrections.