I have very efficient enclosures they take around 4-5 hours to drop 10ºF, for me this is the first thing short power failures of a few hours are no concern.

The second line is a catalytic heater much like the posted buddy heater, that with a couple of tanks buys some more time. Although carbon monoxide is a concern with them as well!

The third line is a set of heat packs (they too use oxygen so still care must be used) if the power looks to be off longer than 24 hours I transfer all the snakes to snake bags and place them in a ventilated cooler I can then use less energy to heat that small space longer.

I have had a generator and looked at others. No a basic generator is not wired to the home and requires a person to start it. The thing to watch out with generators is the power output many are 'dirty' power and can cause stats to fail open full power. to my knowledge in portable gens Honda and Yamaha are the only 100% safe units.

If you are looking at home back ups generac, is the name I know is stat safe. these units wire into the house and have a transfer switch that when the power fails start the generator and feed power to the house with no input. My work runs them and the power just flickers, that is all. They typically run propane or natural gas, not gasoline, or diesel. They are predictably expensive.