Friston's Free Energy doesn't have its own page. But I think a lot of the PCT-relevant conversation on LW, ends up under that term. Unlike the "mostly just intro-posts" under the PCT term proper, FFE seems to have more-recent engagement, so I think FFE has more of a presence here than PCT.
In retrospect, not including those was a mistake.
Here's a (non-exhaustive) handful of the FFE posts:
In trying not to be vague, I veered towards writing too much. So if someone could take what I wrote and destroy half of it (or destroy all of it, and write a new and better thing) that would be lovely.
(In a slight inversion of PCT, I feel very sick of looking at my own writing.)
Pretty sure we had quite a bit more discussion of PCT on here in the last few years, would be great for someone to add it.
I share the impression that there's been a bit more talk and thought on it.
But I tried out the obvious search terms on here, and for the life of me I can't find it. (Other than a few side-mentions, which it didn't seem worth tagging.)
Free Energy Principle gets mentioned a few more times, but I don't know that it's quite the same thing.