In Europe, and I think in much of the rest of the world except the US, isopropane or butane is used in common household refrigerators. Recently EU regulations were changed to allow these to be used in small split AC's as well, provided some flammability precautions are taken in the design and installation of the units.
In principle you could also go without phase change refrigerants with the reverse Brayton cycle, essentially running gas turbine cycle in reverse. But AFAIU these are not competitive with phase change refrigerants in the usual temperature ranges used for AC's and refrigerators.
Yes a propane/isobutane blend works well, it's basically a drop-in replacement for R-12 in air conditioners. Straight propane replaces R-22 in freezers.
The only drawbacks are that it's flammable, and that for the blend, if there is a a slow leak, the blend ratios change due to different partial pressures of the two gasses. So to recharge, you basically have to vacuum the system and refill with the proper blend.
Ammonia also works for industrial applications (the local ice rink uses it) but due to its toxicity it's not ideal for household applications.
I did a quick search on how much refrigerant is in a household refrigerator. Internet says 30 to 180 grams.
I wouldn't be very concerned with 100 grams of propane. Your kitchen has probably 20kg of air. You ain't going to get even close to the flammability limit releasing a 100gm of propane into it.
R22 is also flammable. But probably not as much as propane. But you aren't going to get anything dangerous with the small amounts used in HVAC. It would need to be a propane/pure oxygen mixture to even approach danger.
https://en.wikipedia.org/wiki/Tert-Butylthiol - Because propane is delivered as a liquid and vaporizes to gas when it is delivered to the appliance, the vapor liquid equilibrium would substantially reduce the amount of odorant blend in the vapor.
In principle you could also go without phase change refrigerants with the reverse Brayton cycle, essentially running gas turbine cycle in reverse. But AFAIU these are not competitive with phase change refrigerants in the usual temperature ranges used for AC's and refrigerators.