It’s possible but will require a bit of work: first, OSBee uses the Arduino pin 9 to generate a high-frequency PWM signal for the boost converter. Pin 9 is internally tied to timer 1. In order to change it, you will need to bend pin 9 on OSBee out (so it disconnects from Arduino pin 9), and solder a wire to connect it to some other PWM-capable pin. For example, pin 3 or 11 (both of which are tied to timer 2). Then change the code in OSBee’s library functions accordingly (i.e. setting up timer 2 to use the highest frequency, and also set the correct PIN_BOOST).
Alternatively, is it possible to change your other code to use timer2 instead of timer1?
I don’t think Mega and Uno are pin compatible, so I don’t think you can plug OSBee to Mega.