Form Builder comes with many variants. Importing from Google Slides can be done by the following variant
Form Builder Plus add-on
Open Google Drive.
Select the required Google Slides that needs to be imported.
Click on Form Builder Plus.
Click on analyze to analyze the selected Google Slide.
The contents from the Google Slide will be displayed.
Select the required type.
Click on Preview to have a preview of how the generated form looks like.
Click on Create to create a new Google Form where the data will be imported.
Click on Choose to choose an existing Google Form where the data will be imported.