@JC , We can add a windows 10 device image, create a provisioning policy with the image then assign to the users who want windows 10. The cloud PC will be created based on the provisioning package. We can see more details in the following links:
Add or delete custom device images
https://learn.microsoft.com/en-us/windows-365/enterprise/add-device-images
Create provisioning policies
https://learn.microsoft.com/en-us/windows-365/enterprise/create-provisioning-policy
Overview of Windows 365 deployment
https://learn.microsoft.com/en-us/windows-365/enterprise/deployment-overview
Hope it can help.
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