What constitues a cutting edge firmware?
You can see them listed at https://www.espruino.com/Download#banglejs2 - it's what gets built from the absolute latest code on GitHub.
Can it be true that some of these actions will kill boot code or maybe just clear any intervals?
No - the boot code should always get loaded unless you do the very specific https://www.espruino.com/Bangle.js2#resetting-without-loading-any-code
@Gordon started
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.
You can see them listed at https://www.espruino.com/Download#banglejs2 - it's what gets built from the absolute latest code on GitHub.
No - the boot code should always get loaded unless you do the very specific https://www.espruino.com/Bangle.js2#resetting-without-loading-any-code