I haven't flown with meat, but I have flown cheese back in checked baggage from France a few times, a 9 hr flight.
At least twice, I sent a little battery thermometer that records min and max in my baggage with it. Never has it come out more than a degree or two higher than when I reset it before closing the luggage, even in August. I think I recall seeing a low in the 40's F once, but I can't remember what time of year it was. I suspect the cargo hold is much colder than the overhead bins. Maybe I should send the thermometer in the outside pocket of a checked bag next time?
The first time I flew cheese home I just wrapped frozen blocks in my clothes in my suitcase. That trip, one was a Reblochon, which I didn't realize is illegal until I got back. It's a soft cheese, and it was still cold but got warm enough to deform.
Since then, I've used a small Icemule cooler inside my checked bag. It works great; rolls up small for the trip over, and stuff is just as frozen as it left on the way home.
Of course, none of that has happened since the COVID.