The market looks confusing because there's a large gray area of "research chemicals" sold online with no prescription and no clinical oversight, and those sit in a very different category from a prescribed protocol
However, simply having the bottle on your counter is only half the battle
Geng Y, Zheng X, Zhang D, Wei S, Feng J, Wang W et al (2024) CircHIF1A induces cetuximab resistance in colorectal cancer by promoting HIF1-mediated glycometabolism alteration
The practical verdict: NAC and glutathione are complementary, not competitors
In a broad variety of cancers, GSTs are involved in the resistance to several anticancer drugs by their conjugating activity (some examples are reported below)
This approach allows them to serve the research community in a responsible fashion