After a few idiot thoughts/wrong realizations, I finally figured out the problem with the chips I tried before for iQue.
I bought 5, only 3 work. Reasons could be poor storage, they were broken, they were from aliexpress, they were fake, etc.
I only tried one of the bad ones and gave up. So M45PE40s do work, just gotta get them from somewhere reliable (not fun when they're out of production...)
Gonna try selling some iQue WiFi boards to help with that. It'll be $5 here and there but in the opposite direction.

Reactions: SylverReZ and SAIYAN48