Timing app?

Short: I am looking for (foss) recommendations for an app that lets me program various time intervals and then does some notification when they are up.

So last November when the after work cycling season froze up I finally went to the gym, got me a membership at the one with the most group activities/classes(?) because I like committing to a schedule and to be told what to do. Also the group energy does help me pushing. But I started looking at the quite well equipped gym and somehow I got kettlebells in my youtube recommendations. And then other strange stuff like EMOM and AMRAP.

And the gym have no good clocks...

So when (pretty much always) I want to do some AMRAP (conditioning?) I have to rely on my clock. But its timing programming is really limited, essentially just active/rest. So I need something more robust and after a cursory look at apps I have found nothing. I NEED recommendations.

Example: I want to program a AMRAP session of 1 minute active, 15 seconds reset to next move(?). Do that for 5 cycles. Then a 2 minute break. And start from the bottom. Just an example.