Filtering by MP_Node tree?

Question

Django

I have models structure like this (Django-Oscar):

from treebeard.mp_tree import MP_Node


class Category(MP_Node):
    name = models.CharField(_('Name'), max_length=255, db_index=True)
    ...

class ProductCategory(models.Model):
    product = models.ForeignKey(
        'catalogue.Product',
        on_delete=models.CASCADE,
        verbose_name=_("Product"))
    category = models.ForeignKey(
        'catalogue.Category',
        on_delete=models.CASCADE,
        verbose_name=_("Category"))

I need to get all categories that have products, or have products in child categories. Can I somehow give such categories by means Djangoand filters QuerySet?
Option: get QS, then run through it and check if there are products in the category or in the child ones - I will use it in the end if nothing helps.
PS. If you decide vlob, then something like this:

qs = models.Category.objects.filter(
    depth=1, site=Site.objects.get_current()
)

categories_pks = []
for category in qs:
    category_descendants_and_self = category.get_descendants_and_self()
    for child_category in category_descendants_and_self:
        if models.Product.objects.browsable().filter(
            productcategory__category=child_category
        ).exists():
            categories_pks.append(category.pk)
            break
return models.Category.objects.filter(pk__in=categories_pks)

But how to speed up the code above?