I am in a couple threads discussing this, so I apologize if this is doubling things up.

To be redundant (for absolute clarity) you know how to use Webpack, you do use it, it offers value to you, but not for building websites? Can I assume it only has value (for you) with building complex webapps? (can I also assume this is for Node.js?)

At this point I've used it for web pages, web apps, Electron builds, and haven't needed to but could have also used it for Node.JS server apps as well. Webpack is certainly flexible enough for all of the above.

Aren't Electron builds done with Node.js though?

https://electronjs.org/docs/tutorial/about

This says it's made with Node.js...

Electron embeds Node.js, of course, but from a platform standpoint feels sufficiently different from a Node.js server application (the more traditional use of Node.js) or console application (a growing usage of Node.js) that it can be useful to make a distinction. Especially, because the bulk of an Electron app in my experience is running in the Chromium web renderer process(es) ("client side") than in a more traditional Node.js process.

One technique I used to build an electron app was developing in the browser, and then using a webpack plugin to copy the generated bundles from my web app into a shell app & trigger the electron build. In this way I wrote one version of the code which ran in both browser & electron app. I have used the same technique for other platforms like Cordova