There's a surprisingly large cohort that believes a matrix layout is ergonomic—as in, "I have an ergonomic keyboard". From my personal use, it's a wash at best—some keys are easier to reach, and others are harder. The worst part is the layout promotes ulnar deviation even more than does a standard keyboard, and ulnar deviation is a major contributor to RSI. (A split matrix-style keyboard would negate the ulnar deviation concerns.)
The Atreus layout, while not a personal favorite (way too much chording, which I found unpleasant and uncomfortable), would seem to be pretty ideal on a laptop, though it does take up a good chunk of space.
> From my personal use, it's a wash at best—some keys are easier to reach, and others are harder
I agree.
> the layout promotes ulnar deviation even more than does a standard keyboard
Hard disagree. You may choose to hold your wrists in such a manner that this is true, but that's on you.
I'm a touch typist, and I switched to ortho partly because it makes a lot more sense for touch typing. Touch typing is taught in columns, and when those columns are slanted like this \ there really is no justification. So ortho lets me scratch that itch to fix the keyboard.
The Atreus layout, while not a personal favorite (way too much chording, which I found unpleasant and uncomfortable), would seem to be pretty ideal on a laptop, though it does take up a good chunk of space.