Bravo. This is my dream and also my nightmare. I was super into the quantified self movement a while back, before Apple Watch, writing Withings Scale API wrappers in Ruby and Fitbit days.

Every time I try to seriously track metrics of my life, the excitement of the insight gets worn away by the friction of recording and managing. I expect LLMs can help reduce the cost of this by an order of magnitude but then, as you mention, the question is, what do you do / change / learn because of the data?

I recently started tracking nutrition macros with an iOS app MacroFactor which I really like. This is the first time taking my weight doesn't feel like a IDK SHRUG moment and I can actually map my food intake to my weight.

Finances is probably the other highly actionable data source that is such high friction to manage (downloading CSVs, OFXs, monthly...) that it has always been a false start for me. I finally wrote a service to talk to Plaid directly and I successfully used it to categorize my business expenses at tax time. I finally have programmatic access to my bank account data!

You conclusion is definitely a cautionary take: > the main conclusion is that it is not worth building your own solution, and investing this much time.

But, perhaps a subset of that data you find useful.