@Olivier-202, Thanks for posting in Q&A. You can enroll these personal devices into Intune, and deploy policies, set rules, configure device features, and more. This depends on your requirement. For Android, iOS devices, you can use app protection policies that focus on protecting app data, such as Outlook, Teams, and Sharepoint. For windows device, Intune marks devices that are Microsoft Entra registered as personally-owned devices.
https://learn.microsoft.com/en-us/mem/intune/fundamentals/deployment-guide-enrollment#personal-devicesWe can enroll the personal device via company portal. As a note, please ensure the enrolled user has Microsoft Intune Plan 1 license. After the device enroll into Intune, you can deploy app in Intune.
https://learn.microsoft.com/en-us/mem/intune/user-help/enroll-windows-10-device
To deploy Windows Defender via Intune, you can add it via Microsoft Store new app.
https://learn.microsoft.com/en-us/mem/intune/apps/store-apps-microsoft
Hope the above information can help.
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