Wasn't that a specifically advertised copilot feature? Does copilot not actually support it? They are still claiming to support this it seems https://support.microsoft.com/en-us/office/create-a-new-pres...
They push the "generate image based on prompt" as the main add for slides to make them not just bullets, but no real foundational slide creation is baked in.
Things may have changed since I demo'd it ~6 months ago.
Google Slides is just generated images and transform text as far as I've seen.