I would argue that they are simply constructs. By definition, there is nowhere in the universe where there is nothing. The simple act of observing nothing would make it something, so nothing is not something we could have learned from nature. 0 is a concept humans have created.
Definite nothing, the absence of something? there are spaces between things, that could be considered nothing, unless there are no gaps between matter.
'nowhere' a location, depending on the existence of something, since locations must be relative to something, is that correct?
There may be nothing, in the same way that there are shadows.
0 might be a concept our ancestors learned, when a neighbor stole all of their food. 'Many' sheep yesterday... '0' sheep today!
There is reality, and then we make sense of it with concepts.
A cat doesn't exist, but the reality (physics) underlying the 'cat' causes us to observe it, and label it 'cat'.
Observing 'no-thing' is a lack of observing 'some-thing'. If at any time we don't observe some-thing, that's no-thing, or 0.
This being true or not, doesn't seem to affect my life in any way.
I'm going to order pizza....something infinitely more meaningful.