Tandara I'm afraid I don't follow... I also don't think I know enough about how all this works to give a definitive answer.
We know notifications work whether an account is logged in or not. It's possible Google has two different workflows, one for devices with logged in accounts and another for devices without logged in accounts, or the way it's done avoids being tied to accounts altogether and works the same either way. I'd guess it's the second one since it's the easiest.
Regardless of how everything is done on-device and on Google's servers, it doesn't matter much. It would make sense that Google would be able to figure out all of the tokens used by one device, whether there's a randomly generated device identifier that Google knows, or by IP addresses, etc.
Keep in mind that notifications can be empty, or app developers can encrypt notification data. For example, Signal notifications are empty and all they do is wake up the app so it can fetch data from Signal's servers and display the notification. Unfortunately, it's also possible for notifications to have data in plain text. It all depends on how the app and its servers are programmed.
Not sure what your goals are here, but using profiles might be helpful?