A really simple approach we took while I was working on a research team at Microsoft for predicting when AGI would land was simply estimating at what point can we run a full simulation of all of the chemical processes and synapses inside a human brain.

The approach was tremendously simple and totally naive, but it was still interesting. At the time a supercomputer could simulate the full brain of a flatworm. We then simply applied a Moore's law-esque approach of assuming simulation capacity can double every 1.5-2 years (I forget the time period we used), and mapped out different animals that we had the capability to simulate on each date. We showed years for a field mouse, a corvid, a chimp, and eventually a human brain. The date we landed on was 2047.

There are so many things wrong with that approach I can't even count, but I'd be kinda smitten if it ended up being correct.