Bicycling

I used to live in northern Vermont and bicycle was my only transportation. I live in a more temperate region now, but my partner has Reynaud Syndrome, so the challenges persist. Just not for my hands.

For sub-zero F temps, pogies are the way, although it sounds like they aren't quite working well enough for you. For long rides, I put a chemical handwarmer in each pogie, and that let me run a lighter glove. While wasteful, there are ways to mitigate the consumption of disposables.

For my bike without pogies, I used Pearl Izumi AmFib lobster claws. Those served me well to -28F, which was the lowest temp I saw when I lived there.

The following isn't a gear solution per se, but more of a prophylaxis: hunting reaction training. Our peripheral blood vessels rotate through a set of responses when exposed to cold. That rotation is called "hunting." It's "simple" to retrain our hunting reaction to maintain blood flow to hands and feet when cold. And holy hell, it's unpleasant. The short of it: keep your hands and feet hot while letting the rest of your body get cold. Like serious discomfort levels of cold. Do that for an hour everyday. For me, I noticed improvements in about ten days, and then only need maintenance training every few weeks and again in late Fall. My partner's Reynaud flares dropped to maybe once per winter after ~20 days of training.

The source you want for hunting reaction training is Army Cold Weather Warfare (Research Center?). I'm on mobile and can't find the original paper right meow.