Only consumers can push manufacturers toward kid-sized ergonomic setups. Kids wear kid shoes, so they should use kid-sized keyboards, and so on. Inadequate circulation sets up the hands for strain. Children should prehydrate by drinking juice or water before computing. This helps open the microcirculation to the hands.
Fingerless gloves can be helpful.
Those with poor posture are at risk. I have videotaped my children to show their postures to them. Ergonomics begins with proper posture. Those who do a lot of non-essential computing and video gaming are at risk. Feet should be flat on the floor.