For NB-IOT applications, voltage is about 3.3V to 3.8V, and the transient current varies from 200mA to 1.5A depending on the application.
For the NB-IOT applications, the battery is only 300mAH. The voltage of the battery will pulled less than 3.3V sometimes, which will break the system.
So buck-boost is good for this kind of application to keep the system stability.
MAX77827's quiesent current is about 6uA, and the efficiency is above 90%. The transient voltage changes between buck/buck-boost/boost are quite small compared to other chip vendor solutions.
These are good for the NB-IOT applications too.