The only reason CFCs exist is because the US established a de-facto ban on propane as a refrigerant. You can't trademark, copyright it, or any other form of IP.
It seems for refrigerators there are actually specific carve outs in EPA venting regulations to allow R-290 (propane) along with a couple others.
https://www.epa.gov/snap/substitutes-household-refrigerators...
If vendors don't use it, possibly due to flammability, whether a real risk or as imagined by consumers that's a completely different situation. I can't find anything claiming it's banned or even discouraged by the government.
The explosion risk (in a commercial setting) is mitigated by having gas detection sensors and an exhaust fan that runs when the gas detection alarm trips along with horn/strobes at any entrance to the mechanical room and inside the mechanical room.
In a residential setting, I’d only feel safe if the condenser (outdoor unit) used propane with a liquid to liquid heat exchanger and separate glycol loop that runs inside to the air handler coil.