We can quite quickly create such Time Tracking app (without timesheet so far). In fact it will take few minutes. The tricky part is Formula for Total Time Spent. While we do have formulas, they are extremely hard to setup so far.
This is how you can create Time Tracking app
And this is how formula works
Time list inside Task should be improved to display more info. It will be done in future. I just show how it can work.