Well apparently on another forum they're saying that all this does is switch the power from 3.3V to 5V. They're saying that the boost converter output pin will be reading 3.3V. I'm unsure how to completely switch off power from the converter until the button is pressed
Yes, that's correct. You can see that DC voltage from 3.3V will flow through the inductor, through the schottky diode to the output 5.5V labelled line.
So you would need to add your power mosfet following the Boost converter to switch the output on/off.
Your control circuitry would then optionally enable/disable the boost converter, as well as the output mosfet.
The impression of the initial post is to control power safely. If that is the case, then mechanical switches with latched behavior and/or mechanical relays might be better. They behave more robustly for the state/transitions during power up/down and for failure scenarios.