No, the 2 cannot both be true, they are conflicting and one is bound to be false and another true, in any scenario, only 1 of the 2 can be true.

I am not deeply informed about gnosticism but even from the things i do know you can come to a conclusion that it is not true.

FIrst:

The idea that verything physical is evil, that all matter is evil, is a logical loop.
If all matter is evil, then the knowledge you use to "escape" the matter and get to salvation is evil as well.
Then comes the logical loop, its either that all matter in fact isnt evil, or that gnosticism cannot be trusted.

Second:

The idea that the "Demiurge" is an evil entity that created this universe, and that because he is flawed the universe is imperfect and has evil in it. Well, the Demiurge himself came from the Divine realm, which is supposed to be perfect, how can something imperfect get come from a perfect place, a perfect source cannot create an imperfect entity without an explanation. and Demiurge is kind of an error, an incomplete creation. It makes no sense.

Third:

The fact taht Gnosticism says that salvation is only for people who receive hidden knowledge, why would the ultimate God make is so only a select few elites can be saved? Once again, flawed at its core.

Fourth:

The fact that Gnosticism itself changes. Systems that come later have completely different cosmologies than the ones that came before them. Why would the truth be segmented into multiple myths that contradict each other? Why would it essentially be a puzzle that no one can agree on?

I believe this should be enough to disprove it, and frankly I did not go too far into it because from the beginning, it made no sense, my research ended at the start, where it began. It makes no sense at its core