

Only activating the fingerprint reader when the screen is on is a regression compared to the rear reader. It means I need to squeeze the phone to unlock it, vs just placing my finger in the right spot. It also negates the purported advantage from the comment above mine about being able to easily unlock the phone while lying on a table.
I’m not arguing that the power button reader doesn’t work for anyone. I’m saying that it is qualitatively worse UX for me in particular.
Sounds like what you want is tracing. OpenTelemetry is the de facto standard for that. Couple it with aggressive sampling (here’s a great talk on it https://www.usenix.org/conference/srecon24americas/presentation/cruz ) and you’ll have a very efficient way of identifying use patterns.