If you've got an iPhone, kick it into airplane made and open up "notes" and tap the microphone to transcribe. It even gets "one third plus one half is five six

If you've got an iPhone, kick it into airplane made and open up "notes" and tap the microphone to transcribe. It even gets "one third plus one half is five sixths" transcribed as `1/3 + 1/2 is 5/6` and "four feet two inches" becomes `4'2"` without a network connection. So I believe its doable... I also believe that Apple spent bit to make it that way. Note that the voice to text on the device cuts down on data use (I believe - I haven't sniffed the traffic to verify) and cloud side processing (its working on text rather than audio - its a few pennies less per request). But beyond that... every home voice assistant that I've seen (other than Apple, Amazon, and Google) has worked on pre-programed phrases that need to be spoken rather than the more free form way people speak... and again, that's even without trying to translate that into other infrastructure beyond the device. I'd honestly be happy/impressed to have a RPi based system that can handle taking "create a reminder for next Wednesday at 9:30 am to thaw the turkey" and have that feed into other useful systems. I'd be very impressed if I could do a "create a reminder" (what is the reminder for) "go to parents" (when should I remind you) "Day after thanksgiving" (what time on Friday should I remind you) "half past one" (is that one thirty in the morning or in the afternoon) "afternoon" -- this works with Alexa. Note the recognition of holidays, the 'wizard' style entry and the alternate time format.