Manually copying Google Sheets macros from one spreadsheet to another can be time consuming and error-prone. This Google Workspace Add-on automatically copies a script project and attaches it to a user-specified spreadsheet. Though this solution focuses on Sheets macros, you can use it to copy and share any container-bound script.
Are you looking for a way to centralize your codebase but deploy it to container-bound scripts? Here is a tutorial for you from the Apps Script samples on the Google Developers site, highlighted by Steve Webster, which gives an alternative approach to deploying as an add-on or sharing a container-bound template.
In the tutorial, you’ll find code that uses the Apps Script API to perform functions like getting, creating, and updating container-bound scripts. As part of the solution you’ll see how you can get the source project content using the Apps Script API, then opening a target Google Sheet to either create or update the container script.
This solution is not limited to Google Sheets only. You can use the same process to update code in other Google Workspace editors like Docs, Forms, and Slides. Usually, I would recommend maintaining and distributing your code as an add-on, however, in certain scenarios, this alternative approach could work well.
Source: Copy macros to other spreadsheets | Apps Script | Google for Developers
Member of Google Developers Experts Program for Google Workspace (Google Apps Script) and interested in supporting Google Workspace Devs.