At the moment, no. And honestly that might be too much to send back in a single response (we have implementations with 100s of categories and 10,000s of SKUs).
Could you explain in detail what you’re trying to do from the API client perspective?
We could probably add an endpoint like this, so that you could retrieve all products under a single category.
GET /api/categories/:id/products
That way you could iterate over the categories
GET /api/categories
and then fetch the products for each category.
Otherwise, you to pull all products (including category)
/api/products
and then let the client build the category-to-products map.