Is it possible to integrate my Google Form with a third-party service (like Mailchimp) and trigger a confirmation based on that integration?

Yes, many integrations exist (e.g., using Zapier or IFTTT). These services can trigger actions based on new form submissions, including sending a customized confirmation email through Mailchimp or another platform. The confirmation message in Google Forms itself might be a simple 'Thank you, your information has been sent!' while the detailed confirmation comes from the integrated service.