With Creator Studio, you can easily convert your Google Slides presentation into animated GIFs and video slideshows. The add-on can also extract speaker notes from your slides and export them as a text file in Google Drive. Internally, the app uses Google Apps Script to export Speaker Notes from your Google presentation and writes them to a text file inside Google Drive.
In this post Amit Agarwal share some very clean code for iterating across each slide in Google Slides and export the speaker notes into a single file. Click through to the post for the source code.
Source: How to Download Speaker Notes in Google Slides – Digital Inspiration
Member of Google Developers Experts Program for Google Workspace (Google Apps Script) and interested in supporting Google Workspace Devs.