This is another post where you'll likely not want to emulate me. Despite being a middle-aged broad, I don't give much thought to ergonomics and my writing setup.
I don't write at a desk or a table, which is where a lot of ergonomic preventative measures are applied. Instead, I am Goldilocks, sitting in whatever comfy recliner, armchair, or couch fits my mood. Sometimes I use a cushioned lap desk to elevate my screen; though most often I just eat more holiday cookies to fluff up my thighs. {cough} {looks askance}
I write on my laptop (backlit keyboard + number pad). I don't own a desktop, and the few times I've used my phone for working on the WiP were total disastrophies. I've had the big ol' 18-inch screen and the small tablet 11-inch, but find a 14-inch or 15-inch is the sweet spot for text-heavy work. The only thing I hate about composing on my laptop is that the trackpad is centered under the QWERTY keyboard instead of the whole keyboard. I'm forever right-clicking when I want to left-click because of that. (Yes, I'm a PC user. Yes, I must have the number pad or I'll really go 'nanners.)
I don't use voice-to-text for drafting; though, that may be a "yet" statement. Mostly because speaking the punctuation breaks my train of thought faster than seeing the world's longest run-on sentence on my screen. For me, there's something almost subconsciously affirming about the clickety-clack of typing that keeps me in the creative thrall. That said, I do use text-to-voice for editing. I like having the computer read my mss back to me so I can catch missing and redundant words, along with nonsensical statements.
So far, I'm fortunate to not suffer carpal tunnel, so I don't need a wrist brace. I am diligent about getting up and taking a short walk every two hours to avoid blood clots (my dog is trained to pester me at the appointed hours).
Looking up/away frequently from my screen to allow my eyes to shift focus happens whenever I think, so I've got that guidance well covered. My computer screen is permanently set to "night mode" to minimize blue light. Recently, the news that viewing the world through rose-colored glasses helps relieve light sensitivity for migraine sufferers crossed my feeds. The power of FL-41 tint could be pure marketing hype or it could be scientifically proven, either way, I just received my pink glasses.
So, uhm, yeah, thar' be the ways this couch potato avoids the ouchies of sitting on her ass all day. 😇