IME IP addresses handed out by my phone’s tethering mode aren’t stable, so it’s sorta more of a hassle than just fishing out the little cable and letting my script run. (The device assigns itself a stable IP address on the USB interface.)

Although I haven’t looked at those addresses in some time; perhaps they are more stable now than they used to be.

Good point, I've resorted to nmap in desperation in similar cases but would hope there is a more elegant solution.

It’s easier than that with the remarkable tablet — the device documents its current ipv4 and ipv6 addresses. But it’s several taps away, and then typing on the laptop keyboard, whereas USB is just a connector away. Plus, you need to charge anyways.