I forgot the baking powder ugh hope it turns out

There's a huge difference between coconut milk in a carton and a can (canned has a lot more fat, and possibly flavor?). But it works well with carton coconut milk, huh? I assume you only use the unsweetened.

It was deleted because it may not have worked out that well based on comments but it was to try using 1 cup silken tofu puréed in place of the four eggs. I added it back with a note from the comments.

You can use paper towels to absorb excess moisture from the tofu. Also, I don't bake when I make custard with tofu.

The tofu did not work for me at all. It came out of the oven MORE liquidy than when it went in!

You can use heavy cream, but it won't have the same coconut flavor.

Yes. You can use any sweetener, including all powdered stevia. Please see the linked sweetener conversion calculator to substitute with any sweetener.