Well, both are [not] right. Most ergonomic keyboards are not split - those that are may be the extreme. But cupped keys is an ergonomic feature too that some keyboards have, some don't - and that is why no one can tell you what keyboard to get - you need to go to a computer store and touch and feel as many as you can for yourself. The perfect keyboard for someone else may feel horrible to you, awkward to use. Or it may take up so much space, there's not room left for your mouse, or so small you can't breath when typing.
The QWERTY keyboard layout is pretty standard yet there are hundreds of well-made, quality keyboards out there simply because we all have our unique keyboard requirements - whether we are aware of them or not, or care. Some like mushy, short travel keys, others like keys to give away quickly after a firm press. My wife likes Microsoft keyboards with the keys in curved but flat rows like the MS 6000
- not split, not wavy, but ergonomic because she doesn't have to bend her wrists outward. For me, I've been using A4Tech boards for 20 years because I like the feel of their "Natural A-Shape"
keyboards for a similar wrist straightening effect. They have keyboards with cupped or rounded edged keys. Waterproof too. I am sure Logitech has similar stuff, and like the others, keyboards of all shapes and sizes.
Same story for a mouse. Get one that feels good in your hand or both hands, if you switch back and forth every 6 months or so to keep the carpel in check.