The following Google Apps Script is designed to create a Shortcut to an existing Google Drive folder, within another folder..
For Google Drive pros you can currently place a file in multiple folders, but Google will be removing this functionality on 30 September 2020. In March Google announced general availability of shortcuts in Google Drive, is is designed to replace the ‘file in multiple locations’ feature. For Google Apps Script developers wanting to migrate to Drive Shortcuts Phil Bainbridge provides this useful Apps Script snippet.
Source: The Gift of Script: Create a Shortcut in Google Drive
Member of Google Developers Experts Program for Google Workspace (Google Apps Script) and interested in supporting Google Workspace Devs.