I can't speak for Thrive Market, I'm not sure why they'd list something as Whole30 compatible that has any sweetener in it. If you remember the particular product that had maple syrup listed as an ingredient in the Whole30 compatible list, could you let us know? I can pass that along to HQ so they can look into it.
The Primal Kitchen Ranch with Avocado Oil is fine to have. If you look, the ingredient that is asterisked as adding a negligible amount of sugar is lemon juice concentrate, and that would be the naturally occurring sugar in lemons/lemon juice. I'm not sure why they needed to put that note there, but it's not the same as actually adding sugar to the product.
From a Whole30 perspective, there is a class of products that are Whole30 Approved, which means there's an official relationship between Whole30 and that brand, and not only are their Whole30 Approved products compatible with the program, there are other standards like if they contain animal products the brand meets certain animal welfare standards. You can read about the Whole30 Approved program here: https://whole30.com/whole30-approved/.
So anything that is Whole30 Approved is also compatible, but there are plenty of foods that are compatible with Whole30 that don't meet the Whole30 Approved standards, but they're absolutely fine to have. Whole30 Approved does mean it is Approved and good to go (but do double check each product, some brands have products that are approved and others that aren't).