I have Hashimoto’s and Sjogren’s disease, and every few months or so just one or two fingers have Raynaud’s. I typically suck on those fingers to warm them up and shake my hands hard to get the blood flowing. It’s stupid and annoying but hasn’t really bothered me.
ETA: It’s amazing how many of us have an autoimmune disease. I consider rheumatologists “doctors of last resort.” If regular doctors don’t know what you have, you get sent to a rheum.
Back in the days when I worked from home I fantasized about inventing a heated keyboard. I never got around to that but now I see that there are heated pads you can put under your keyboard that sounds like they might solve the problem of cold hands.https://www.amazon.com/Heated-Desk-Pad-Mouse-Shut-Off/dp/B0DC7TRL94/ref=sr_1_3?crid=3AODZUHHB8E2J&dib=eyJ2IjoiMSJ9.UGgZ7UZRY3Mv3wd4JvmIK29QbyDjeYTO8VNY7DxrNeAJPC54uY5uRqvVFQDBVbLNMNzHql9lfV3FcI8z19jYXUZ2ojbZ1c_BkGnK9QQGJQmy4pXE_tyAjDKnRSOPeLTlcL6nsiKDSoLaz0medpDg5I4G96Mh8gGOb2FwzLePsMVq77St3bJPurVVmFS3Z5yVsc_1vuWE_vKFbq-17evj3paInF9TfQcq9c5SH-e9raQ.mIbv-WAcLteQpKjQrlWslOcN3QaZPmGz2rRTelb_Sfo&dib_tag=se&keywords=heated%2Bdesk%2Bpad&qid=1769978578&sprefix=Heated%2Bdes%2Caps%2C451&sr=8-3&th=1
I have had it for quite a few years and am very interested to read others’ experiences in this thread. I’ve been tested and have some early markers for autoimmune disorders. This winter has been particularly hard for me as it has been unusually cold here in the south. I’m affected more in my hands than in my feet. It can be hard for me to handle cold & frozen items when I grocery shop and also to hold cold or frozen drinks (I usually try and wrap a napkin around it). I’ve been surprised how many people have it - either I mention it or they notice my blue/white fingers and comment that they also suffer from it.
Merely wearing gloves or mittens doesn’t help me. I need an actual heat source to battle it. My heated steering wheel in my car has been a life saver. When I am the passenger in a car with heated seats, I sit on my hands 
I’ve been thinking of trying the rechargeable hand warmers. Many years ago I was on a medication for it (may have been the same one mentioned upthread). It was something that opened up blood vessels. It worked for Raynaud’s but made my face flush, which I didn’t like, so I stopped taking it.
I don’t know if there is any science to support this but I also notice that it can come on if I am extremely upset or stressed about something (which thankfully doesn’t happen often).
Dr Goolge says that stress can be a factor in having flare ups.
This. If my hands/feet are cold, putting on gloves/shoes seems to just keep them that way longer. I’ve also found that polyester/fleece (aka plastic based cloth) don’t work for me either. It makes me overheat and then I can’t disperse the heat.
Wool gloves, wool base layers, wool socks. Those have worked the best for me. When I worked,I wore alpaca fingerless gloves thatran past my wrists. I have to be careful with external heat sources (like hothands, or electric warmers) bc I can’t always feel the heat enough to avoid a burn.
I recently bought rechargeable hand warmers from Amazon. They have been a game changer for me, but I hear you about having to be careful with them.