Is an FPV controller any different than a regular video game controller? I interested in how hard it is to fly a drone even in a sim environment.

The left stick is generally used for throttle and is not centered with springs but rather adjustable and holds its position in the Y-axis direction.

You should be able to use the controller calibrator to calibrate a regular video game controller and use it.

Only use the upper half of the left stick per the spring issue folks mentioned above.

Yes, one of the axis on FPV controllers usually is not springing back to neutral position, for throttle. This may seem like a small difference it is important.