I made a new profile and installed Gboard and Google Play services. I enabled "faster voice typing" and after a while I revoked network access permissions on Gboard and was able to use voice dictation without any problems.
I then tried the same thing on my main "owner" profile, and cannot get it to work no matter what I do. If I revoke network permissions on Gboard, voice dictation does not work and I just get a message saying "cannot connect to google right now".
I'm totally confused. Does anyone have a solution for this?