1. Don't forget to pre-freeze the insert of your ice cream maker per manufacturer's instructions!
2. Regarding the peanut butter: it doesn't have to be chunky. But it does have to be no-stir. If you use the all-natural kind of peanut butter that naturally separates in the jar -- even if you stir it up the best of your ability -- the ice cream just won't be super smooth and creamy and scoopable. This might mean having to buy your favorite store brands' Peanut Butter "Spread" (usually containing some kind of oil and sugar). Or just the good ol' Jif or Skippy. While these usually aren't preferred products in our house, I'm happy to make the exception for exceptionally creamy results.
3. Regarding the non-dairy milk: While I am fairly confident that this Almost Vegan Peanut Butter Ice Cream recipe would work with any full-fat non-dairy milk, the one that we've used for consistently creamy dairy-free peanut butter ice cream is Oatly -- specifically, Oatly Original in the light blue package. Low Fat Oatly doesn't achieve quite the same results, and I haven't tested it with Full Fat Oatly, but I know from using it in place of the Original in other recipes that it's much richer and more viscous, which could affect how the ice cream freezes. (Let's remember: there's plenty of fat in the peanut butter already, and when there's too much fat in ice cream, the texture can go from creamy to waxy.)