It's a Pro Micro DIY build! Much like all the other ones.

Can accept either a Heltec HT-RA62 (contains SX1262 radio) or an EByte E80 (contains LR1121 radio) radio module, as well as a Pro Micro nRF52840.

Also has space to fit an OLED, and a cheap CN3791 solar charger board on the bottom. And GPS if you want?