Sounds to me like you need different bundles for different pages. While the brunch configuration is typically in brunch-config.js it also supports
-c, --config [path] specify a path to Brunch config file
So you could simply have a separate configuration for each separate bundle and move the script tag for the bundle from the “layout” to the “page” so that each page references the actual bundle that it needs.
Now other tools can support multiple bundles per configuration - for example rollup’s configuration file can be a single configuration object or an array of configuration objects.
