A monorepo I guess. It looks like Microsoft is using a monorepo for their office applications (https://rushjs.io/) and you could do the same thing for node.js using yarn workspaces/lerna/rush.

Each "Microservice" could live in a separate package which you can import and bundle into single executable.

Elixir has "Umbrella Projects": https://elixirschool.com/en/lessons/advanced/umbrella-projec...

Rust/Cargo has workspaces: https://doc.rust-lang.org/book/ch14-03-cargo-workspaces.html