Yeah. There’s an option with blue bubbles on the Mac that keeps it awake. I just always keep the lid open

I own a Mac and a pixel 8. I use blue bubbles. It works great. Don’t have any issues with it. When you send messages through it, it goes through your email associated with your iCloud account

I mean… Couldn’t smart watches do the exact same thing?

You can also set up a VPN on your pi and always be connected to it while you are on cellular. Just take a little bit of extra work