Does anyone have any recommendations and experience with this?

Not a garage door but on a metal sheathed outside door. The only cutting tool I recommend is a small 3" grinder with a metal cutting wheel. This is the one I use. My 4 1/2' grinder is too bulky. The first time I drilled starter holes then used a hacksaw blade. That was a uneven mess

https://www.amazon.com/dp/B09L..._b_fed_asin_title_12

By garage door do you mean a roll up type? Insulated or not?
Will the pet door fit inside one panel with room to spare and no braces to cut?
A better option would be if there was an exterior swing type door to install it in. Pull hinge pins and lay door on sawhorses to cut opening. Clamp a board for straight edge and use a circular saw with appropriate blade (wood or metal).

I have never put one in a roll up and would be concerned about structural integrity, especially if it was a wide door.

Wish you the best with your project.

only thing I've got to say is I've got one of these.
https://www.hitecpet.com/products/autpetdoorfo

they make a through the wall version, which I'd use in a garage setting.

Roll-up type, non-insulated. As to fitting inside one panel- I haven't measured, but it would have to.

The most common pet doors have an inside and outside piece and fit a door 1 & 1/4" to 2 " thick.
The outside is mostly a trim piece, and the inside piece is where the plastic flap attaches.
If there is a clear flat space for the size you need then you could build a wooden frame to fill in for the thickness needed.

Like this?

That fits in the bottom panel of an overhead garage door.

https://moorepet.com/doors/garage-overhead

A friend had one installed. so, his cats could come and go as they please. His Cat food started to disappear really fast. then he figured out the coons were helping themselves to an easy meal

Since the metal in the door pictured is rather thin, I would built wooden “picture frames” to go on both sides and screw them together. Then mount the dog door to the frame.

Get a pet door with the little RFID sensor that goes on the animals collar and unlocks it when they are within 6 feet or so. Keeps other critters out. Have used one for years and they work great. Just have to change the batteries in the door every 6 months or so.

quote:

Since the metal in the door pictured is rather thin, I would built wooden “picture frames” to go on both sides and screw them together. Then mount the dog door to the frame.

I'd use PVC "wood" to eliminate rotting issues.

From the company the Monkey referenced, this one is electronic and uses the cat’s internal chip, if he’s been chipped, for $111:

https://moorepet.com/cat-mate-microchip-cat-flap-360/

It’s only $18 more if you need a chip to hang on a collar.

If I’m reading it correctly it will work on a thin metal door with no adapters.

Neighbor's dog was attacked by coyotes. They ripped him apart. Dog used one of these doors.. I never let my dog out unless Im with him... Here in Az we have coyotes, bobcats and mountain lions all formidable foes..