Some of the recordings are unintentionally hilarious though, it turns out. When I looked at the history page, there were a bunch of times when Google seemed to think I was saying "b b b b b b b b b" repeatedly? Anyway, when I played the audio back, it seems my alarm clock's beeping had triggered the Google Assistant, which then obviously failed to understand the beeps!

You can also replay the audio from all your Alexa commands in the app. In iOS it’s in Settings -> Alexa Account -> History.