Converting a recipe to vegan

I've got a recipe for a pumpkin corn chowder that I feel is pretty close to vegan as-is, but there are a few things I know need to be swapped. I was hoping to make this for my vegan in-law as a surprise otherwise I'd just ask them. 😅

The broth is basically vegetable stock and pumpkin, cinnamon, nutmeg, salt, and sugar, so I think that's fine as is, right? To that I add sauted onions and corn, which is my first question: rather than butter, what kind of oil is best for sauted veggies? The original recipe called for chicken which obviously I'd skip or maybe replace with tofu cubes? I'm not super fond of the texture but it might work. The final thing I don't know about is adding half-and-half. I've read coconut milk is a good substitute for heavier dairy products...is that a good swap? Does it carry a heavy coconut flavor to it as well? There's a lot of subtle flavors coming together and I'm not sure how coconut would affect that.

Thanks for any help and suggestions!