Many eons ago I wrote a Python version of tmpcli for this exact reason. Made some minor improvements a few years ago but haven’t touched it since. Curious what methodology Codex came up with, I haven’t revisited it since models got really good.
The idea is that tmpServer listens on localhost, but dropbear allows port forwarding with admin creds (you’ll need to specify -N). That program has full device access and is the API the Tether app primarily uses to interact with the device.