Even many HVAC contractors are under informed here - my guy thought my Carrier heat pump didn’t work under 35 degrees until I showed him the manufacturer documents. Don’t go with a company that uses “rules of thumb” from 1985 when modern sizing and commissioning requires heat load calculations based on your building construction and specific details from the unit spec sheets.
https://www.mitsubishicomfort.com/blog/mythbusters-heat-pumps-for-extreme-cold-climates#:~:text=Hyper-heating systems can perform,low as -5° F.