> I can sign into my Mac and get text messages.
Doesn't this actually depend on relaying the SMS from the phone? I don't think delivery works if your phone isn't in range of the laptop.
Even the watch seems to require the relay to work for receiving [1]:
> To receive SMS, MMS, or push notifications from third-party apps on your cellular Apple Watch, your paired iPhone must be powered on and connected to Wi-Fi or cellular, but it doesn't need to be nearby. You also need to be signed in to iMessage on your iPhone to use Messages on your watch.