Fascinating.

My question: how does this affect Drake's equation?

https://en.wikipedia.org/wiki/Drake_equation?wprov=sfla1

One of Drake's factors is

fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space

The article doesn't explicitly state it, but it's imaginable (since I've just imagined it) that the set of circumstances described as necessary for the invention and perfection of the steam engine could be so unlikely as to make our own planet the only one in the galaxy to have developed such technology.

Or maybe something of the kind is inevitable after a few thousand years of agrarian civilisation.

Who knows?