I've suffered with Reynauds for many years (so did my Mum).
I have tried every possible combination of gloves/mitts, to no useful result.
Gloves are no use at all as they isolate your fingers.
The only solution I've found is to use pogies (bar mitts). They create a warm microclimate without restricting what little circulation I have. I wear very floppy thin mitts as well so I can put my disposable hand warmers actually on my fingers inside them. The best pogies are made in Nottingham from the sort of material Carradice use for saddlebags, called Hotpogs!
https://www.hotpog.co.uk I regard them as suitable only for flat bars. I purchased some of another brand that are designed for drop bars, but because they sit vertically they make the bike uncontrollable in even the lightest wind. I need flat bars anyway because I now find it difficult to use drop bar shifters and brakes.
Mine are bright red - it aids visibility! And there's actually room to stash flapjack etc in them. The mid range £60 version - a mere fraction of what I have spent on gloves over the years.
Yes, they do look "distinctive", yes they are a bit clumsy. But it does mean I can trundle round the North Pennines all year round, and that is worth the trade-off.
Avoid neoprene - it does not work for me - or anyone else I know who has Reynaulds.
I also avoid waterproof gloves, which tend to make my hands sweaty, then very cold.
Other advice as above - keep your whole body warm, especially wrists and ankles and neck, where your blood is close to the surface.
Put on warm clothes immediately you stop - I really can't do mid-ride stops in winter any more.
Your GP can prescribe meds, which some folks find very effective, but I want to avoid that route as long as possible