Is there any substitute for coconut milk in Thai and Indian curries?

I'd use half-and-half, or a touch of sour cream or full fat Greek yogurt (depending on the dish) if I were allergic to coconut but wanted a bit of creaminess in the dish I was making. I've never had a nut milk that I'd use in a curry. Others may have . . . I sometime use smooth almond butter to make vegan soups "creamy." They work for that purpose. For a curry, though, I'd probably just use a somewhat rich dairy product. ;o)

It's not the fat, I'm just allergic to coconut. Wondering if another nut milk might give the same silkiness.

Some Indian curries use dairy cream.
If you are trying to get away from the excess fat from coconut milk and cream try using a puree of silken tofu or mimic cream vegan creamer.