Old PebbleKit Android depends on app and Pebble app sending broadcasts on every update. Not only is this extremely insecure (every other app on the phone can listen in on those), it is also not working anymore when targeting new SDK versions, so it cannot be used for the new apps (Cobble / Core Devices).
Here is my proposal on how can we create a modern, more convenient and more secure version. It is loosly based on the way WearOS communications work.
Note that "Pebble App" below refers to any Android app that communicates with the watch directly (such as Cobble).
I presume that most apps (both companion apps and the Pebble App) will be written in Kotlin, so following examples are in Kotlin. To support apps written in Java, we can either write the SDK for Java and provide Kotlin wrappers or write it for Kotlin and provide Java wrappers (since Java apps are in minority nowadays, I would go for the latter).