Using Google Keyboard privately
spiral it can do, having tested GBoard myself there doesn't appear to be a real issue with IPC as every function in the settings appears to respect the Network permission state and reports back that it can't connect to Googles servers.
My caution was more theoretical than practical as far as I can observe.
For those having issues, to get GBoard and Google Camera working, I had to ensure that I installed all the Google Play components from Apps first, THEN install GBoard and Google Camera. Once this was done, I removed the Google Play components once again. GBoard and Google Camera now continue to work. Doing it the other way around (GBoard first) resulted only in constant crashes.
Anyway, the general advice is to have Google Camera or Gboard installed on a profile without any of the 3 google apps. And network disabled of course. That's the only way they can't trasmit any data over internet, as far as I understand.
If you do this, do updates continue to come through for these two apps?