Not quite what you’re asking for, but during WW2 the US employed Navajo speakers to use their language for certain verbal communications because it was so different from popular languages and hard to decipher. There’s a lot written about them out there. I would also recommend checking out The Code Book by Simon Singh, it’s a great recap of the history of secret codes and breaking them.

what if it needed just one more second to complete?

they may be able to read certain data from another instance but their current platform allows complete surveillance of what you looked at, how long, every click and scroll, etc while also being able to feed that in to manipulating what you see.

imo it will be basically impossible to have that kind of impact on people from instances not controlled by them, particularly if the other instance defederates so they don’t see meta instance content.