@kozuch, these motors do not seem to have enough thrust to lift the combination of NAVIO2, Raspberry and themselves. You’d need something more powerful if you want to get in the air IMO.
The NAVIO PWM rail is aimed at providing PWM signals to drive an ESC or servo, and also at distributing 5V power if a source (such as an ESC bec) is attached to the rail. I personally would not recommend driving a motor using the current from the signal pin, since it is most certain that it will not be enough, and worst case you could even damage your hardware.
To drive a brushed motor you have a choice of drivers, starting from simple H-bridges to complete brushed ESC circuits.