GitHub Actions evaluates each step by the exit status of the process it runs. The runner marks a step successful when the command finishes with an exit status of 0. If the command returns any other code then the step is marked as failed and the job may stop depending on your workflow configuration.

GitHub Actions encrypted secrets can be accessed in workflows using the secrets context. You can directly reference the secret within an if: conditional using ${{ secrets.MySuperSecret }} to determine whether a job or step should run based on the secret's value.

[A] Some actions may require a GITHUB_TOKEN as an input to authenticate and perform specific tasks, such as creating issues, commenting on pull requests, or interacting with the GitHub API. In such cases, you would need to explicitly pass the token to the action.
[B] When making an authenticated GitHub API request, the GITHUB_TOKEN is required to authenticate the request. This token is automatically provided by GitHub in the workflow, and it must be explicitly used when interacting with the GitHub API.
Note: You can use the GITHUB_TOKEN to make authenticated API calls. This example workflow creates an issue using the GitHub REST API:
Reference:
https://docs.github.com/en/actions/tutorials/authenticate-with-github_token

The best way for an enterprise to control which GitHub Actions run is by creating a list of approved actions as an enterprise policy. This approach restricts workflows to only use the actions that are explicitly allowed, ensuring security and compliance within the organization.
Note: To allow a specific list of actions at the GitHub Enterprise level, an administrator must navigate to Enterprise > Policies > Actions and select "Allow select actions". Then, from the dropdown menus, they choose "Allow selected actions and reusable workflows" and add the desired actions to the allowed list using the format OWNER/REPOSITORY@TAG-OR-SHA.
These actions can also include local actions, actions from specific organizations, or specific tags or commit SHAs.
Reference:
https://docs.github.com/en/enterprise-cloud@latest/admin/enforcing-policies/enforcing-policies- for-your-enterprise/enforcing-policies-for-github-actions-in-your-enterprise

REST API endpoints for workflow jobs
You can use the REST API to view logs and workflow jobs in GitHub Actions.
Download job logs for a workflow run
Gets a redirect URL to download a plain text file of logs for a workflow job.
Code samples for "Download job logs for a workflow run"
Request example
Get /repos/{owner}/{repo}/actions/jobs/{job_id}/logs
Reference:
https://docs.github.com/en/rest/actions/workflow-jobs