I'm an indie that travels a lot. I'm interested in it to have more flexibility with ergonomic setups for development, such as being able to stand without needing a way to elevate my laptop to eye height (it's easy at least to find ways to get my keyboard halves to proper height for standing) or lying with keyboard halves at my sides.

Curious if anyone is using it successfully for ergonomics (not just for the convenience of having a big monitor which is secondary for me - Macbook + iPad sidecar display is very travel-friendly but very difficult to use ergonomically away from home).

I can't see any realistic way that the ergonomics would be better than your haphazard hotel room setup. Reality is that the device still has weight on your head and neck and is still kind of tiring to wear for long periods of time.

It's still 1.5lbs hanging off the front of your face and over hours that's still straining.

Lying down or in a recliner or something where you're not really having to support the device yourself is about the only way that I feel you might achieve any kind of better result in an ergonomics sense for a significant length of use time.

(Disclaimer: I had one to demo for a few months and used it/experimented with it sporadically, I don't own one.)