No timers yet. Pick a duration above.
Five minutes away from the screen, with a clear start and a clear end. Set it going, stand up, stretch or refill the water, and the double chime calls you back; until then it makes no sound at all.
An open-ended break tends to swallow the half hour after it. Five minutes with a clear end makes standing up easy and coming back automatic.
No. The countdown follows the clock in a background tab, so leave the desk entirely; the chime still calls you back.
Add it as a browser source in OBS; the background stays transparent. Change t for any length.