Not ganging up on you in any way here but I agree with @UKHeliBob … the name is not good. It almost makes me think your code is going to explode my eeprom or nvs….
One comment from a non proficient coder here. The code seems very complicated for a beginner to use and The basic example shows how to commit to memory but then what?? How would a person “read” or “retrieve” the data/variable stored in memory? I think personnally you need more examples, more details in your comments as well to explain for basic people like me.
First look at eeprom.h and preferences.h for me and i know how I should code it to try and learn. First look at yours and i am confused and have many questions.
I don’t doubt your coding skills and what you claim as I am not a coder BUT
honest feedback is good right?? 
