Some cloud services for the device are actually optional. But AFAIK you still need a Google Account.
Here is the help page on the topic of data collection and privacy:
https://support.google.com/onhub/answer/6246642?hl=en&ref_to...
And see also, how to set a whole bunch of privacy settings:
https://support.google.com/onhub/answer/6279845?vid=1-635755...
Disclaimer: I work on the project. I am not a spokesperson or legal or marketing, or anything like that.