The specialized hotwalk is awesome, an amazing little thing, my son (now 4 yr old) learnt on it and still loves riding it even though he’s graduated to a ‘proper’ bike and my nearly 2 yr old can’t wait to use it.
It has a low slung ‘top’ tube but the saddle/seatpost join means that the saddle can’t be put as low as you think it ought to, meaning that there is a bit of a minimum height/leg length to be able to ride it.
The ridgeback scoot looks like it might be more suitable for a smaller rider, but i’ve not really investigated it.