Here's a quick list of useful commands that may not be directly supported by the library but are handy for many projects!

RI on SMS receipt

AT+CFGRI=1

The RI pin will pulse low for ~100ms when an SMS is received

Factory Reset

ATZ

will reset the FONA GSM module to its factory default

Bluetooth commands

Here's a thread if you're interested in the BT support in the SIM800H (there's no antenna for BT in the SIM800 breakout but it is in the FONA feather)