I don't deal with the same cold riding, but I use them in winter back east and they are great for skiing and usual cold activities.

The them is a pair of black diamond ski gloves. They are great in the raining and freezing riding and I have used them without issue down to -8°C or so without issue. They are a bit bulky shifting but as long as you keep focus on the task it easy enough. But also my bike is outside always and the shifting issues could be dirty cold frozen cables and housing. After three or so winters they are done so not a bad investment near $100 dollars.

Anything dry or damp and above 5°C I use my kayak gloves, they actually work really well keeping wind out. They double as my xc ski gloves and driving gloves.