This is the reason most children's pillows quietly fail, and almost nobody selling them will say it out loud.
You can choose the most carefully engineered pillow available. Correct height, correct support, shaped by experts. None of that matters on the nights it is not under your child's head.
And a plain white foam block is easy for a child to ignore. It looks like something for grown-ups. There is no reason for them to want it, so it drifts to the edge of the bed, or onto the floor, and they curl back up on whatever they already love.
A pillow can only support your child's position on the nights they actually sleep on it. Not beside it. On it. That is the part most brands design around instead of for.
Bombees was built the other way round. The same premium ergonomic foam that keeps the head in line, wrapped in a soft cool-touch cover, in animal designs your child picks themselves, with gentle fidget ears and a tail they can hold as they drift off.
It stops being the pillow you bought them and becomes the one they reach for. And the pillow they reach for is the only one that can help at all.