Let's say I want to hack my psx games so i can have any items i want in any game.
What I would have to do is find out where in memory my inventory items id's (in hex obvisously) are stored.
Correct me if i'm wrong, in order to to this I would have to make 2 memory dumps, one with any specific item on my invetory, and the other memory dump with that same item moved out of my inventory, right?

The emulator I'm using is psx v.1.13, i've run the emulator's debugger, i can check the memory monitor, but you cant do nothing with that but read it. There isnt a single basic function such as goto, search or even dump which is what i need....

are these data in savestates compressed? or they represent memory just like in the debugger?

Or you could use PEC, press CTRL+D, and get an instant memory dump with nothing else but RAM.