Still unsure if I want to join the challenge, but I can contribute a tracking tool that has been working really well for me. After survey time track apps, I settled on Toggl Track. It's free. It works on computers and phones and synchronize data.
I have a computer right next to my digital piano. At the beginning of my practice session, I press one button on my Elgato Stream Deck to start a timer on Toggl for my "Piano Practice" project. At the end, I press that one button to stop the timer. It couldn't be any simpler than that. And I have exact time I played every day for 6 months now.
My next wish is to have an easy way to track time on each item of my practice. I know it can be done by jotting down notes in a journal, but that's to much effort.