InTune Android connection "unexpected error"

I've never encountered this issue before with Intune/Google. My first guess would be that it has an issue with the account having a Google workspace License. Intune and Workspace aren't really a match made in heaven. 

Just to rule this out, you could create a standalone google account that is not part of your tenant and see if that connects properly. 

When reaching out to Intune support, I suggest escalating to the manager. All support agents list their manager in their signature, if things don't go as you wish you can forward a message to the manager. They will always escalate, and i've had some good experiences with that level of support.