This post serves as a permalink to accompany my talk from EmberConf 2021.
The demo of the service-worker-based build tool is available here with instructions to run both the prebuilt binary (currently compiled only for OSX, sorry!) as well as how to rebuild everything yourself.
It's demo quality. There are pieces of it that are still scaffolded. I implemented enough features of the Embroider v2 spec to get realistic results, proving that we can, for example, crawl all the addon metadata and combine their public assets. I didn't implement the full spec yet, so a few things are handled in app-specific ways. I do think the results are representative, and I intend to keep developing mho until it's a production-quality build tool.
To run an Ember app with standalone webpack, here's a sketch of what your webpack config needs to look like. Thanks to Kris Selden for sharing his: https://gist.github.com/krisselden/7a988d65a7481dac1450dc3ae934f692