You can embed a Google Slides file by logging into your Google account, finding the Google Doc file you want to embed, and follow the instructions to pubish to web, then pasting the public share URL into a Pitchdeck layer’s Embed input field.

Example Google Slides URL

https://docs.google.com/presentation/d/e/2PACX-1vTxJhs1SMd4q3t78e-n8-cwAYEVgOrEHMDl-xCkTUCJJbObv6syRsuYjjIWYPGmiTTk8944Uz_6RzB8/pub?start=false&loop=false&delayms=3000