To make a frozen pizza crispy with an inverter microwave, you should use an appliance with a grill function. These manage to create a browning process and provide toasted aromas.
Depending on the appliance, it may be necessary to heat up the pizza first with a defrost programme and then use the grill function to bake it until crispy. Some microwaves come directly with a special pizza function that does just that.
A little tip from the editors: If you have an inverter microwave with hot air, it works just as well!