The Arduino MKR WAN 1310 developer board can bring LoRa connectivity to projects without requiring continuous mains power. The board is just 67.6 x 25.0 mm and integrates an ARM Cortex M0+ processor. The MKR WAN 1310 is available to order now for €33 (~US$37).
https://www.notebookcheck.net/MKR-WAN-1310-Arduino-introduces-a-new-developer-board-with-LoRa-connectivity.440425.0.html