Who'd think that @RIOT_OS can also run on #Riotee boards?
Granted, piggy-backing on another board can barely be called elegant, and it's using none of the low-power infrastructure, but hey, it's a start.

"#Riotee can only work when the harvester provides sufficient power. Do not expect to collect data at night with a solar-powered device." #gnihi

Love this: the #Riotee is a tiny #IoT board built around the #NordicSemiconductor #nRF52833 and is battery free! They provide a solar shield and a capacitor should to run the device. Removing the battery makes devices much more sustainable.
https://www.crowdsupply.com/nessie-circuits/riotee