I just made a similar comment. The large building I normally work in has gas forced air and radiant floor heat. They renovated a big storage area to offices and used mini-splits and they work fine as they connect to the gas fired heat areas as a supplemental heat, even in the low 20’s.
The smaller building got converted to heat-pumps when the 1990s furnace died. Works fine to the upper 30s. Almost All the exterior rooms have some portable electric heater for the cold days. They can’t keep up, especially if you have to open the door often.
low 20’s is a heatwave in some states mid winter-