It doesn't even look perfect - rounded shoulders, forward head, not much lumbar curve. Probably all inevitable when you have a tiny keyboard and screen is way too low.

Also, good posture in a chair is nearly impossible to have, let alone maintain. I've started working from the floor and sitting with my feet/legs in a variety of positions - immediate and immense improvement in my posture, overall mobility and reduction in pain.

Yes. Middle of ANY screen should be at eye level, including treadmill workspace.