Yes, it does. Most numbers are just read from the BMS. A few is (probably) calculated with the help of read numbers.Just installed the "scan my Tesla" app and an OBDII dongle in my Model 3 (delivered Nov 2021, one of first 60kwh LFP cars). According to the app, battery was 60.5 kwh when new, and is now 56.5 kwh. Mileage is 29,915. I believe the app is just reporting numbers from the car's CAN bus, so this is what the car believes the battery capacity is.
Nearly 7% degradation in almost 2.5 years. From the graph posted by @AAKEE a few posts up, that's slightly better than expected.
Yes.