In the settings for your Google Form you can edit what appears when people successfully complete your forms. You can include links to external websites in the "successful submission" field that appears when the form is completed. Watch this video to see how that is done.
Video - How to Redirect to Specific Pages After Completing a Google Form
Applications for Education
For many years I put links in the "successful submission" message to redirect students to activities that I wanted them to do after they finished a quiz that they had taken in Google Forms.
Learn more about Google Forms in my playlist of Google Forms tips and tricks.