Nothing is the absence of absolutely everything: no matter, no energy, no QM, no potential.
That is something science can not accept because I can not test for it. The only way to arrive at your concept of nothing is to exclude every other option and I can't. In principle I can agree that an area has none of the things you list but that still takes me short of calling it nothing. You know about the conjecture of quintessence how would I exclude things like that scalar field being there?
Science has the situation of predicting dark matter but unable to find it, and not having a full theory for gravity. You also saw how hidden the Higgs field was and what it took to make it testable.
So can I realistically ask would it be safe for science to say anything conclusive about the concept of nothing?
For nothing to become something, or something to become nothing would necessitate the violation of the laws of physics.
Again whilst I agree with the thrust of the thought you forget that is true of the universe we measure and see here and now. The problem is the big bang directly contradicts that statement in that we have a huge amount of energy come into existence.
So we are left with two choices, one of which I think is the one you have selected
1.) The energy that came into the universe from the big bang came from something before/outside the big bang or something in physics we have not yet understood. This says the law of conservation always and absolutely holds.
2.) The laws of physics have not been constant throughout the history of the universe. The conservation law does not hold in some epochs of physics but it is valid and holds in our current epoch.
Science is actually in favour of 2 because of how the fundamental forces seem behave as you increase the scale of energy. As the energy is increased the various forces seem to merge together and so it leads to a prediction that all the fundamental forces merge to just one at the point of the big bang (
https://en.wikipedia.org/wiki/Grand_unification_epoch).
It is hard to determine what physics looks like in such a epoch and that includes whether the law of conservation is going to hold. Most guesses are conservation doesn't hold because the whole thing looks like it is unstable.
So I would like you to tell me how and why you exclude option 2?
How safe do you feel you are in excluding 2 without any data from that epoch?
