Well the IOS app inexplicably started working! I have successfully set
up both my cameras and my doorbell. I encourage everyone who was having
issues before in the IOS Google Home app to try again!
https://www.googlenestcommunity.com/t5/Cameras-and-Doorbells/Something-went-wrong-message-while-installing-google-nest-camera/m-p/3932
No solutions yet, sadly
In a different thread about the same issue, someone said they were
having the same problem and using IOS so switched to using an android
device for set up and had no issues. Seems like it may be an IOS issue…