Good find, very cool device, so small too. The GM02SP LTE-M/NB-IoT is also a 5G modem that's probably why its quite expensive but definitely future proof. Some of these advanced ESP32 integrated modules really pack a punch.
I also found a Chinese board called the KC868-A2. It has a set of headers suitable for a 4G module (not 5G yet) designed around the Simcom 7600 family. It also has ethernet on board, two relays and a RS485 line driver. I have this A2 board but haven't ordered a 4G modem for it. (I use it for ethernet, I2C and RS485 mainly). Very nice construction and can be purchased from AliEx economically (including a case for DIN rail and flat mounting). For Australia the module needs to be selected carefully to be able to include band 28 which is 4G at 700MHz (SIM7600G). The 7600E is ok covering other 4G bands but could limit application in regional or remote areas.
VK3UU
