In a Google Doc you can insert a Table of Contents to provide a link to each section in the document. This is not a function in Google Slides. If you are creating a Google Slides lesson for students it can be handy to provide linked text or a button to have students jump to different parts in the Google Slides.
This is an unofficial Add-on. This means I have not submitted it to Google for review (this takes months and lots of hassle). You will need to use the template to manually install the Add-on each time. It will give you a warning screen that the app was not reviewed by Google (this is correct) and to make sure you trust the developer. Alice Keeler is the developer! You can trust me. You may need to click on "Advanced" and "unsafe" (it is safe) to authorize yourself access to your Google Slides. It takes about a minute for Add-ons to load in the Add-on menu. Look for "Table of Contents."
Copy and Paste Your Slides
The Add-on script is bound to the Slides template. You will need to copy and paste your existing slides into this template. You can also use the File menu to "Import slides."
Table of Contents
The first option is to "Make Table of Contents." A new slide will be added to the front of the Google Slides. A list of all the slides in your Google Slides will be created with a hyperlink to jump to that slide. It creates each of these as an individual textbox so you can move and arrange the table of contents however you wish.
The other option is to create a button for each slide. Choose "Boxes TOC" to add a button for each of the slides, hyperlinked to the slide.