This featherwing board adds cellular connectivity to the feather ecosystem. Due to the XBee form factor, it can accommodate any hardware in the xbee form factor. The unique feature about the cellular module is that it can operate as a slave as well as a stand-alone module that can be programmed in micropython.
The cellular module can be replaced with other xbee line of products. The design files and firmware examples are available in the Github Repo.