I ended up building something similar but way smaller in scope -- just a cron job that pulls Apple Health exports, bank CSV dumps, and git commit stats into a single SQLite db. The queries that actually proved useful were embarrassingly simple, stuff like correlating sleep hours with commit frequency or spotting that my spending spikes every time I start a new side project. The real 80/20 of personal analytics is just getting your data into one place where you can join across sources. Everything beyond that is diminishing returns.