Yes Raul, it is possible for computers that are not registered in Intune but have Microsoft Defender installed Microsoft Defender for Endpoint allows you to manage security policies for devices that are not enrolled in Intune through the Microsoft Defender console.
Here are the steps to achieve this:
Onboard Devices to Microsoft Defender for Endpoint: Ensure that the devices are onboarded to Microsoft Defender for Endpoint. This can be done through various methods, such as using a local script, Group Policy, or Microsoft Endpoint Configuration Manager.
Take a look a this documentation
https://learn.microsoft.com/en-us/mem/intune/protect/mde-security-integration
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