Neither knowing your phone number nor the Cloud Act nor both in combination gives Signal the magical ability to “snoop” on your end-to-end encrypted chats or to circumvent Sealed Sender, if that's what you're trying to express with your PII argument. https://signal.org/blog/sealed-sender/
Long-term secret keys and session keys are generated and stored on the end-user's device and are never sent to the server. It's called end-to-end encryption for a reason. Wiretapping doesn't change that.