Clockify's desktop app has a "mini timer" feature (see screenshot) that reduces the app's size so that you can keep it "always on top" without it getting in the way. At its smallest size, the TMetric Desktop app is way too big to always keep on top, so I tend to minimize the window and then will often forget it's running.

It would just need to show a running timer, start/stop button, and perhaps the active task (same as Clockify).