The first thing I'd recommend if you can swing it is short term disability insurance. If you have that available to you, it might be worth considering.
If not, you may find voice dictation programs useful in some cases, like writing documentation, slack messages, and so on, but that may be more trouble than just typing one-handed depending on various factors. That said, while I can't remember the guy's name or conference talk off hand, there was a video I saw once about a (I think Python) developer in a similar situation who built a voice dictation system for programming and demo'd it live, and he was very effective with it. Seemed like it had a hell of a learning curve, but depending on how long you'll be unable to use that hand, it might be worth your while to do some research in that area.
My last bit of advice is probably the most practical but least desirable: get good at typing one-handed. Back in high school I dated a girl who unfortunately had to have one of her arms amputated when she was a kid. I always wondered how the hell she was able to use AOL instant messenger (showing my age here, haha!) so well, until I saw her type at home in her room one day. Despite having only one hand, she could type just as fast as I did, maybe even faster! (And I've been considered by most people one of the fastest typists they've ever seen; this girl put me to shame!) She'd been doing life one-handed for years, so of course she got good at it. Moral of the story is: yeah it sucks and it's gonna be a rough transition, but you CAN get better at the one-handed thing eventually, just like she did.
No matter what you end up doing, I wish you luck and a speedy recovery!