The tutorial for running Webpack on the Google Cloud Platform assumes a nodejs runtime. Is there a way to run it on an existing app that's running Python? I'd like to start sprinkling the app with some Webpack+ React love.
GAE allows your app to have multiple modules, and there is at least some support for having different modules use different languages, but I haven't tried it myself.
One important question is whether you are using the "Standard Environment" or the "Flexible Environment" for your app. Node.js is only supported on the Flexible Environment. See here.
So if you are able to use the Flexible Environment, it may be possible to have a single app with both Python and Node.js. I say "may" because GAE doesn't always support all combinations with its various features.