Replacing Lenovo’s WWAN Unlock Blob with a 100-Line Bash Script

My ThinkPad T14s shipped with an Intel XMM7560 LTE modem that would not register on the network until Lenovo s proprietary FCC -unlock helper ran. I replaced it with a roughly 100-line bash script from a ModemManager merge request, and along the way learned that the unlock is just a small challenge-response handshake that is easy to explain in plain shell.