Hi Noël,
Thanks for your comments on RIOT and on my online course on GitHub.
Regarding low power with loramac on the murata chip, you can have a look at [1] and [2]. The first pr improves the lorawan example application with context persistence on EEPROM, thus allowing OTAA with STOP power mode. Note tha low power modes are enabled by default.
The second pr is meant to improve power consumption on STMs.
Let us know how much power consumption you can reach with them.
Cheers,
Alex
[1] https://github.com/RIOT-OS/RIOT/pull/11237 [2] https://github.com/RIOT-OS/RIOT/pull/11542