“Further development of this device doesn’t make much sense due to the exorbitant costs of Iridium transmission through RockBlock, namely £13 for a monthly line rental and £14 for the cheapest package of 100 credits, which equals 5 kB (!?).”
One hobbyist built an STM32 tracker that reports over LTE every 10 seconds and falls back to Iridium, then sailed it from Tromsø to Svalbard. It worked. The LTE module even found signal before the crew’s phones did. What killed the project was the bill: £14 buys 5 kB of satellite data. Iridium charges by the byte like it’s 1998.