looped_around
It had similar issue. I used it in a secondary profile. I can connect it to the watch but it will never sign in to a Google account. It always got stucked at the "Signing In..." screen forever. In addition to that, once I switch back to the main profile and come back, the watch will never talk to the phone anymore, always discontinued. I tried resetting over and over, no help. The connection only last if you stay within the profile.
However, I don't know if this is by chance or what but I eventually signed in to Google on my Pixel Watch. So what I did is just a reset and pair like I did hundred of times already, but this time after pairing sucessfully, I restarted my watch. Since I did not switch user on my phone it reconnected successfully after the watch restart. And this time, I was able to sign in to my Google account for my watch from my phone. I'll come back to offer update if I have any. Mine is a Pixel Watch 2 LTE given for free by Google from their offer.