Getting all subitems from a list of items with list comprehension

I have a dataclass foo which has a member item_li: list[item], item is a dataclass which has a member sub_item_li: list[sub_item] I want to return list[sub_item] from a method of foo. I am primarily looking for a solution with list comprehension. I got it already working with the following list comprehension which I split into 2 lines:

sub_item_li_li: list[list[sub_item]] = [sub_item_li for sub_item_li in [item.sub_item_li for item in self.item_li]] 
all_sub_item_li: list[sub_item] = [sub_item for sublist in sub_item_li_li for sub_item in sublist] 
return all_sub_item_li

Is there a way to achieve that without having to create a list of lists first?

Answer

Oli answered the question:

return [sub_item for item in self.item_li for sub_item in item.sub_item_li]