Bechamel? Yep. Have made it with cashew and almond milks.
Mashed potatoes? Yep. Made them with almond, cashew, soy, and oat.
Pancakes? Have made them with all kinds of plant milks.
Baking? almost never a big deal…I made clafoutis with Almond milk. I make pumpkin pie every year with coconut milk (no it doesn’t taste like coconut) I have even made ice cream with plant milk.