1. Unlocked bootloader.
2. 4g
3. Works well with android aosp
4. Open source drivers.
5. Bootable from sd card.
6. Works well with fuchsia
7. External keyboard support
A few years ago I bought a couple arduino compatible gsm boards and although they worked well and enabled me to to send data logs from remote devices via sms, after I finished using them, I was deluged with spam sms messages!
Im assuming that while the boards were sending me messages they must have also sent my receiving number to another place where my number was sold to spammers.