Shell to Budgie fork, documentation?

I’m looking into dipping into Applet development. I’ve seen a few applets that are based off of gnome shell extensions.
Where can I find documentation for a shell to Budgie transformation?
Currently looking into forking gnome-rounded-corners for budgie. Seems like a small enough project.

Gnome shell extensions are most often written in a form of java script. These cannot be used in any other desktop environment.

For budgie you will have to interpret the javascript and write the equivalent code in vala (preferably) or in python3

Example budgie applets https://github.com/UbuntuBudgie/experimental

Or have a look at our budgie extras repo

Thanks.
I’ve been looking at the budgie-extras repo.