If you need to include a full Google Slides Presentation into Demoflow without importing it in, you can always publish the Slides Presentation and include the published link in Demoflow. Here's how:
Publish the Google Slides Presentation
- Go the presentation you want to include
- Go to File
- Publish to Web
3. Make sure that you restrict access to only your organization (if applicable)
4. Hit Publish
5. Copy the URL
Add to Url to Demoflow
Create a new URL with that link, and viola! You've got a url with the full presentation.