This information is for developers/curious, arguing why certain design decisions were taken.
By separating the distributable package to its own folder, we can keep its package.json (which gets published) to a minimum.
This also allows separate README files for the repo (how to develop it) and the published package (how to use it).
There is no need for the developer to install firebase-tools (the Firebase CLI) or have a Firebase project.
We do all development using emulation.
Haven't found an obvious "best way" for this. Let's try in some apps and see what likes/dislikes are.