Ah, I’m happy to share.
I built this using the custom button card years ago (so before the mushroom cards existed).
Here my gate has just been opened and the garage has been open for the maximum time. A yellow garage icon means it’s occupied (i.e. there’s a car parked inside). Red means it needs attention (i.e. open for too long).
These are my notifications. The time accumulates until it’s closed.
