Alexa Timer
This app will call a service at the end of alexa timer. You may define from which devices the app will be called. You may also define which "named" timers the app will act, so for example you may say: "alexa, timer kitchen 10 minutes" and have the app acting only on this timer.
The app also support automatically silencing the alexa device after a defined delay, so you may let it ring for 30s and then be silenced.
Please, note that if ask alexa to cancel a timer, the app will also cancel its inner timer.
Note that "devices" and "timer_name" have to be configured as yaml lists (see the example).