also if someone can explain why the A4988 stepper microstepping does not seem to work the way I imagined it would
The gauge motors work on a different principle than the standard two coil steppers. Furthermore, for microstepping to work, the current limit on the A4988 has to set correctly, which is not possible with those high impedance, low current gauge motors.
If you can't get the AX1201728SG chips to work, your only option for optimal performance is to use custom circuitry.