This is the first time I've had a problem I wanted to solve and turned to AppSumo first to see if there was an app here that could solve it. I used ChatGPT to build a script in Google Slides to duplicate a deck and put content in the place of placeholders throughout the deck. But it was glitchy and my patience wore thin. Hence, the search. SlideFill is almost exactly what I had in mind and it works really well for this purpose. Add placeholders in a Google Slides deck, create a Google Sheet that matches up with those placeholders, pair the two together. Great app.

Note: Megan I see your reply below but there's no way for me to reply to it here on AppSumo.