Well, what'd happen is the Bangle.js is 'advertising' - so not actually connected to anything at all.
Then Home Assistant would be able to receive the advertisements and figure out based what is in them whether it should turn the light on or off.
But yes, you'd need an app on the Bangle for that - but it'd be super simple. Basically just something that calls NRF.setAdvertising(...) with one value or another.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Well, what'd happen is the Bangle.js is 'advertising' - so not actually connected to anything at all.
Then Home Assistant would be able to receive the advertisements and figure out based what is in them whether it should turn the light on or off.
But yes, you'd need an app on the Bangle for that - but it'd be super simple. Basically just something that calls
NRF.setAdvertising(...)
with one value or another.