nx:run-script
Run any NPM script of a project in the project's root directory.
Options can be configured in project.json when defining the executor, or when invoking it. Read more about how to configure targets and executors here: https://nx.dev/reference/project-configuration#targets.
workspace.json:
"frontend": {
    "root": "packages/frontend",
    "targets": {
        "build": {
            "executor": "nx:run-script",
            "options": {
                "script": "build-my-project"
            }
        }
    }
}
nx run frontend:build
The build target is going to run npm run build-my-project (or yarn build-my-project) in the packages/frontend directory.
Caching Artifacts
By default, Nx is going to cache dist/packages/frontend, packages/frontend/dist, packages/frontend/build, packages/frontend/public. If your npm script writes files to other places, you can override the list of cached outputs as follows:
"frontend": {
    "root": "packages/frontend",
    "targets": {
        "build": {
            "executor": "nx:run-script",
            "outputs": ["{projectRoot}/dist", "{projectRoot}/docs"],
            "options": {
                "script": "build-my-project"
            }
        }
    }
}