How can I create a set of assetbundles in my build, besides the "main" scene as a regular player executable (or apk, or whatever the current target builds to)? I have found about the post-build step ("PostProcessBuildAttribute"), but it's not clear how I should use it for this purpose. Would it make sense to invoke assetbundle builds from a method marked as such (like, invoking "BuildPipeline" methods from there)?
If you navigate to your project in the web dashboard (https://developer.cloud.unity3d.com/), after setting up a build target you can configure Asset Bundle Options by clicking on "Config", then "Show Asset Bundle Options". From there you are taken to a configuration page that allows you to specify which bundles to build and optionally copy to StreamingAssets.