So after almost 50 years of hacking, I'm starting to feel it in my hands. But I don't have any wrist problems -- no carpal tunnel. What I have is tendonitis in my fingers, primarily in my middle fingers and my right pinky (from slamming Enter several million times).

I've had steroid injections into the tendon sheaths of my fingers a couple of times, which hurts like a bugger when it's done but definitely improves things after a few days. It isn't a cure, though, and my hand doctor thinks I'm going to need surgery eventually.

I have to assume that a split keyboard won't help this. Is there anything that might, short of a voice interface?

Suggestion, don't use your pinky. I haven't used it for over a decade. Instead, move your whole arm as a unit, and primarily use your index finger. It takes some adaptation, but movement is better than stillness the vast majority of times.

As for the tendinitis, have you tried physical therapy for your fingers? Whenever I've had a stupid day of overusing the thumb with my phone, I wrap the smallest possible elastic band around my thumb, and do some curls. Slow and controlled. The mixture of force, movement and stretching feels great, and the issue is gone.

Here is an example band https://www.decathlon.es/es/p/banda-elastica-5-kg-cross-trai... the important part is that it's really thin and light. It should look like a string, not a flat band.

A split keyboard might still bring you some relief. Modifiers/enter/backspace/etc are usually moved away from your weakest fingers (pinkies) to your strongest (thumbs). I have Ctrl, Alt, backspace, delete, space, enter and shift all on my thumb clusters.

Here's an example of what that might look like: https://kinesis-ergo.com/wp-content/uploads/KB360-GBR_FRONT-... (though in the default configuration, shift is still on your pinky; you can customize this on most keyboards, or on OS level).

The rabbit hole goes very deep. Another option is home row mods: https://precondition.github.io/home-row-mods. A combination of thumb clusters and home row mods can reduce your finger strain a lot.

I forget the name of the layout (the board is a Lily58), but my keyboard does away with the staggered key spacing and has keys aligned vertically with a subtle bowling. You're usually pressing keys with your pad, not the sides or tips, and I suspect it would be even better with flat low profile keycaps.

There are some styles of "chording" keyboards that might help too, and some that would be way worse. Chording keyboard are also wildly different to regular keyboards, totally alien by comparison to just splitting a keyboard.

Give svalboard a look. Might be some old threads on here about it.

https://svalboard.com/

Ok, fellow old hacker here. I have a similar problem and I found that a lot of the hand pain was from mouse/trackpad usage. My hands have been a lot happier since going to a trackball because I don't do nearly as much gripping and pressing.

The angle / position your wrist is when your fingers need to do these lateral movements could be more or less taxing depending.