Adapting onto a Price-Pfister bathroom sink faucet with hidden Aerator

After weeks of research I’ve been unable to figure out what the thread size of a Pfister hidden aerator is. I want to remove the aerator and screw on an “instant-off” aerator device.

The Pfister aerator thread size is wildly non-standard. The outside diameter of a removed aerator measures as .73″, or 18.62mm.

So naturally, I figured the threads were 3/4″ 27F, and I needed a 3/4″ 27M adaptor to screw into it:

But that didn’t work. It’s close, but it doesn’t thread.

It seems as if the internal “hidden” threads inside the Pfister faucet MIGHT be MALE threads, with the threads on the removable aerator actually FEMALE 3/4″ 27F. If that’s the case, it’s virtually impossible to screw an adaptor in, because it doesn’t seem that any adaptor would be made with female threads on the outside.

Anyone ever run into this? Or have an idea what the actual thread size is supposed to be?

UPDATE: According to Price-Pfister, the threading of the inside of the faucet is 3/4″-18F, so an aerator or aerator adaptor would need to have MALE threads of 3/4″-18M. The problem is, 18M seems coarser than 27M, and if anything, the threads seem finer. In any case, I don’t think there’s such a thing as an 18M-to-anything-adaptor?

The model number of the faucet is: Pfister Weller LG49-WRO