You can easily add custom widgets in 2 easy steps.
Step 1: Add your new component to the components/Widgets directory.
Step 2: Register your component in the components/Widgets/widgets.js file.
But what if your widget needs it's own vuex store?
Just add a vuex module file for your widget in the store directory.
There are several example files in there already.
But what if I need to run some server-side code?
Lambda functions live in the functions directory. You can add your own by merely creating your function and saving it in the directory.
Note: if you need to use an npm library, you need to add it to the package.json located in the functions directory, as functions are built separately from the rest of the project.