Just wanted to mention another device which is now my favorite for this particular use case.
It’s a small tower table lamp, intended as a nightlight, with RGBW options. it has a press button on top for manual control. or you can control it with a voice assistant or through a SmartThings integration. No custom code needed. And right now it’s on sale for $31. Put it on a small table outside the meeting room, and you’re all set.
Also available in the UK.
This is from Meross, it’s well engineered with good safety features. And also works with HomeKit.
We have two of these and really like them for notifications.