Variables reference
Find information for supported variables, naming conventions, limits, and contexts in GitHub Actions workflows.
Variables include:
* GITHUB_REPOSITORY
The owner and repository name. For example, octocat/Hello-World
* Etc.
Reference:
https://docs.github.com/en/actions/reference/workflows-and-actions/variables

Local GitHub Actions refer to two concepts: custom actions developed within your own repository and the process of running any GitHub Action locally on your machine for faster testing and debugging.
1. Local Actions (within your repository)
Definition:
These are custom actions that you define and store directly in your repository under the .github/actions/ directory. They are not publicly shared, unlike actions from the GitHub Marketplace.
Purpose:
They are used for project-specific, repetitive tasks that you want to reuse within your workflows without publishing them globally.
How it works:
You can call these local actions in your workflow files as if they were standard published actions.
2. Running Actions Locally (on your development machine)
Note:
Pinned repositories
You can give users easy access to important or frequently used repositories, by choosing up to six repositories for public users and six repositories for members of the organization. Once you pin repositories to your organization profile, the "Pinned" section is shown above the
"Repositories" section of the profile page.
Reference:
https://dev.to/codenamegrant/supercharging-your-workflows-with-local-github-actions-2o23
https://docs.github.com/en/organizations/collaborating-with-groups-in-organizations/customizing- your-organizations-profile

Setting exit codes for actions
You can use exit codes to set the status of an action. GitHub displays statuses to indicate passing or failing actions.
About exit codes
GitHub uses the exit code to set the action's check run status, which can be success or failure.
* Exit status: 0
Check run status: success
The action completed successfully and other tasks that depend on it can begin.
* Exit status: Nonzero value (any integer but 0)
Check run status: failure
Any other exit code indicates the action failed. When an action fails, all concurrent actions are canceled and future actions are skipped. The check run and check suite both get a failure status.
Reference:
https://docs.github.com/en/actions/how-tos/create-and-publish-actions/set-exit-codes

The correct option is on: which specifies the events such as push and pull_request that trigger a GitHub Actions workflow to run.
In a workflow file this key accepts one or many events and can include filters like branches and paths for push and pull_request so it defines exactly when the workflow starts.

In GitHub Actions, environment variables can be defined at three different scopes: workflow, job, and step. Each scope determines the visibility and lifetime of the environment variable across the workflow execution.
Variables defined at the workflow scope are available to all jobs and steps within the workflow.
Variables defined at the job scope are available to all steps within a specific job.
Variables defined at the step scope are only available to the step in which they are defined. They are declared within a step and are not visible outside of that step.
Reference:
https://medium.com/@leroyleowdev/github-actions-ways-to-share-data-between-jobs-
4267ff9ac2ce