@Mountain Pond Thanks for posting in our Q&A forum.
After testing, I found that contacts can still be deleted in fully managed devices in kiosk mode, and I didn't find an option to prevent the ability to delete contacts, at least not currently supported by Intune.
And I also searched in Android MDM, currently they do not provide an interface to prevent deletion or modification of contacts, please refer to:
If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.