California is going to have special rules.
Maybe check out the .gov website (and save every page in triplicate)
Furnace and A/C unit outside might need to match. IDK.
Automotive went from R-22...to R-34...to whatever it is now.
Different hoses and pumps and pressures required for each system.
I do like the idea of using cheap common non-flammable gases (seems to be only industrial for now):
https://coolsys.com/co2-refrigeration-systems/
CO2 refrigeration systems are a natural, low global warming potential (GWP), sustainable alternative to using synthetic refrigerants that help you comply with EPA’s HFC phase down while delivering maximum uptime and system performance.
RV and portable units appear to be common propane:
https://heatgear360.com/propane-air-conditioner/
The cooling landscape has evolved dramatically. Today’s portable air conditioners use eco-friendly refrigerants (including propane-based R-290) and deliver powerful performance without permanent installation.