Yes, you can certify any file (AI-generated or human-created) if you want to claim authorship, timestamp it publicly, or prove its origin. For example:
AI-generated images, music, or code
Documents written using tools like ChatGPT or GitHub Copilot
Any digital content you wish to link to your name and a verifiable moment in time
Just make sure that you hold the rights to the content before issuing a certificate. The EMOZ declaration you accept explicitly states that you are the rightful owner, so it is your responsibility to certify only works that you are legally entitled to claim.