As mentioned in my question, the issue is not receiving a notification, but getting the token.

Do I need "voip" in background mode? I'm using pushKit to update complications, this is not a voip app.

I was able to get the token using a different app, with similar configuration. The main difference is that my app is flutter based, and the other one is native. Could this be the cause? Does the watch app needs to talk to the Phone app? (Flutter apps do not load in debug mode on iPhone)