I’ve done a fair amount of reading on ductless mini split heat pumps.  It appears that the more popular models from Mitsubishi and Fujitsu use r-410A, which is far better from a global warming potential (GWP) standpoint than prior refrigerants, like r-22.  I’ve read about r-32 and r-290 being used in some systems internationally.  These refrigerants have substantially lower GWP, which would be desirable just in case there are leaks somewhere down the road.  I have done some looking, but haven’t seen any ductless mini splits in the US that use r-32 or r-290.  Do these exist in the US?  Is there a reason I’m not seeing them available?