> The "killer feature" of PinePhone is that you can SSH into it as any other Linux machine
OP, you might be interested in Android I think. It runs a Linux kernel, you can enable root access, and then use something like Linux Deploy to install a distro of your choosing that runs as though it's a normal app. I've been using that since my first Android device and have been able to ssh into my phone "just like any Linux machine" this whole time.
Indeed, I find it a killer feature and don't understand not more people want to access their DCIM folder via sshfs (bookmark it in the file manager for easy access, never get your phone out of your pocket anymore to send a photo to PC) or make full-system backups via something like restic. I also use qalc as calculator on the command line whenever I need more than simple multiplication. Fully recommended.
(Do use ssh keys instead of a password to avoid needing to type some super strong password on the phone to connect to localhost, since phones get taken into all sorts of untrustworthy WiFi networks)