Nope. But somebody else may know of one that can be properly required (or imported; which is the fundamental issue).

For some background you may be interested in Modern JavaScript Explained For Dinosaurs (no insult intended, I didn’t pick the title).

for font-awesome and glyphicons you need copy cat
npm install --save-dev copycat-brunch

This is for bootstrap sass you can configure if you dont use bootstrap-sass

plugins: {
    copycat: { 
    "fonts": [ "node_modules/bootstrap-sass/assets/fonts/bootstrap"]
              }
}

I ran into that - in my case Phoenix distribution didn’t include glyphicons-halflings-regular - i.e. bootstrap is incomplete.

There needs to be a static/fonts folder with:

glyphicons-halflings-regular.eot
glyphicons-halflings-regular.svg
glyphicons-halflings-regular.ttf
glyphicons-halflings-regular.woff
glyphicons-halflings-regular.woff2

The app.css file has the bootstrap CSS baked in which references these fonts.

2. “eonasdan-bootstrap-datetimepicker”: [‘build/bootstrap-datetimepicker.min.css’], doesn’t look like a path under node_modules (hence the name of the configuration: npm)

You’d have to look at modifying

stylesheets: {
  joinTo: "css/app.css"
},

instead.

The joinTo supports a variety of pattern matching styles.