I've tried using bluetooth mics because my speech isn't great with the vent. They seem worse than the inbuilt mic but I can't get phone to a position where I can read it and be close enough for the mic to always hear me. Latest beta doesn't seem much better. We'll see what the final version is like but I am not confident that it'll be reliable, Nuance struggled with Dragon for Mac for years and never got it right. Mouse control via my chair joystick is still the best thing in IOS13 for me although a little difficult on a small phone screen.