I saw NAC on amazon two days ago after someone recommended it, but it was pretty pricey - about $50+ dollars a bottle - so I didn’t order any yet.
I was going by this:
https://noqreport.com/2021/06/17/nac-being-studied-for-use-against-covid-19-so-of-course-amazon-just-banned-it/
Good news if they are wrong. I have seen similar products, next time I need some - will see if it is there.