Mine is an outdoor cat that lives on the well sheltered porch with a super insulated (about 4 or 5 inches) heated house above the ground by the front door, with the heater bed wattage replaced to adjust to the season, from mere padding to a passive reflective body heat pad, to 5 watts, to 25 watts, to 40 watts during the dead of winter.
I feed and water the cat twice a day and in return it kills everything that moves in my yard, gophers, scorpions, snakes, harmless birds, field mice.
Sounds very much like the shelter we set up in our screen porch for a little feral cat family. Bought a mid-size dog house at the farmers co-op and insulated it. From Amazon we got a hard plastic heating pad for the bottom, and plugged it into a thermostat that would power on if the temperature went down to a certain point. (I think it’s made for chicken farmers.)
We cut a second door opposite the main door since cats don’t like to feel trapped. After the first below-freezing TN months we brought them inside to live.