Not sure where you are, but DS in the UK was prescribed Neocate which is a dairy, soy free formula - it takes disgusting but DS will happily take it as a milkshake (pureed melon mixed into the milk!!) or in cooked food (he is nearly 2 so probably more fussy that your LO will be).
We were told not to give DS rice milk due to inorganic arsenic levels! DS has oat milk which has added calcium, but it's not a high fat content (but he eats sooooo much that his weight has never been an issue, etc and dietician is happy with this).