If you read the Kate M book, (working from memory as I gave it to someone) there is a section that describes the two rescuers who are attempting to head over to Watson Path (breaking trail in deep snow) needing to warm up by heating liquid with a cannister stove (presumably an Isopropane stove but I do not remember a mention of brand but I would guess a Jet boil), the first stove/cannister would not light as it was too cold despite a very major need for it to do so. They ended having to use a second cannister that was way down in the other officer's pack presumably where body heat from the officer would have kept it warmer or the cannister was new and they were successful.
Having lived with a MSR pocket rocket one cold spring on the AT for 5 weeks, I learned the tricks of running one in 30 F temps on occasion and can confirm that they start to have issues around freezing with a new cannister having a range down to possibly 25 F while a cannister nearing empty was showing signs of poor performance in the mid to high 30s. I learned to keep the cannister in my sleeping bag on cold nights for breakfast while generally on most nights it was less of an issue as we normally ate near or before dark before the temps dropped from radiational cooling. There are tricks to get lower temperature vaporization by rigging up a copper heat conductor from the burner and wrapped around the tank but not something to rely on in an emergency. As mentioned, there are a few rare cannister stoves that can be run with an inverted cannister that have a fuel vaporizer in the burner but they are a larger footprint. IMHO for an emergency winter stove, a cannister stove is not the way to go.
The liquid fuel stoves that seemed to be the go to ones for emergency in the past were the Coleman Peak 1 feather 400 or an old Optimus 8R or Svea with the optional pump and tube of priming paste. All three are no longer sold new but used ones are on Ebay and parts are available but require some looking but if you buy one especially the Coleman buy one with low hours and is tested. They all have a small fuel tank of various sizes, (I think the Peak 1 is bit bigger) so no need for a separate one. The Peak one had an optional hard aluminum case that could be used as a pot in pinch. It is probably sacrilege. to some folks, but my experience is the Peak 1 is probably the easiest to use as long as someone didnt try to use auto gas through it at one point. No need to assemble it and it has a built in pump (although priming paste makes it lot easier). The Optimus is probably the smallest footprint but a separate pot will take up space (It can be stuffed with gear). In any case these are not for the fast and light crowd but are darn close to bombproof. The alternative is a Trangia alcohol burner, a lot slower to boil, (one stepup from a can of Sterno) and lower Btu content fuel (1/3 less than Naptha) but no moving parts. If the choice is nothing or a Trangia, go with a Trangia and worse case a can of Sterno.
Even with a small fuel tank, liquid fueled naptha stoves carry a lot of potential heat. There are 250 calories in one BTU. I oz of coleman fuel has 7800 btus or just under 2 million calories, that is a lot of granola bars
and no need for digestion, its near instant core heat.