Answer
Hosted mode: when connected to an external microcontroller, the module can be easily operated using our AT command set.
Hostless mode: Simplicity Studio from Silicon Labs provides full support for development (C Development), while we offer a variety of sample applications to streamline customer development.
Finally feel free to check our User Guide - Firmware Options and Upgrading - RM126x Series that shows and explains all available firmware options and upgrade methods for our RM126x LoRaWAN modules