But can they make any that are in stock to buy?

Ok, but what is cheaper, two Pi 4S one 1 Pi 5?

I disagree. The pi series are never going to do any serious heavy lifting in terms of computation, their niche is lightweight hardware that allows you to decentralise systems. Making a more powerful system at a higher price point isn’t really useful in that case.

I would rather have two less powerful machines that i can install in separate modules to control separate systems, than one centralised machine that’s still not powerful enough to do everything on it’s own. Plus, you get double the GPIO pins if you use two boards.