Can you help me choose a microwave to fit the hole I already have?
Especially how to get the exact size I need?
And how important is "inverter technology?

I need to replace a dead built-in black microwave without spending $800 to
replace it with the original Jenn-Air M170B countertop 1200W 1.6cf unit.

The existing fabricated black aluminum faceplate apparatus is pre-set to:
Length = 22-1/8"
Height = 13-3/8"
Depth = 12-5/8" (but it can be deeper)
Watts = 1200W
Volume = 1.6cf

Costco has a #1325470 Panasonic NN-SC668S for $119.99
Length = 20-7/16"
Height = 12-3/8"
Depth = 16"
Watts = 1200W
Volume = 1.3cf
with something called "Inverter Technology".
https://www.costco.com/panasonic-1.3...100500583.html

Home Depot has a #1003366983 Magic Chef for $109.00
Length = 20-3/4"
Height = 12"
Depth = 15-1/2"
Watts = 1100W
Volume = 1.6cf
https://www.homedepot.com/p/Magic-Ch...1ST2/305708071

Target has a #NN-SN67HS Panasonic for $119.99, which is
Length = 20-11/16"
Height = 12-1/4"
Depth = 15-13/16"
Watts = 1200W
Volume = 1.2cf
https://www.target.com/p/panasonic-1...s/-/A-52689506

Target also has a #072-1-282 Oster for $64.99
Length = 23.9"
Height = 14.4"
Depth = 18.4"
Watts = 1000W
Volume = 1.1cf
https://www.target.com/p/oster-1-1-c...0/-/A-53383982