Yes, you can. I've made the vegan version successfully using soy and rice milk. I've also tried using oat milk, but it leaves too much of an aftertaste. I suggest you use the one you like the taste of or the one that has the least noticeable taste. Plant-based kinds of milk are usually more watery than regular cow milk, so it's important to use more flour in order to get the same thickness of the pudding base, that is - roux.