Hello Edgar, 

I have inquired with our OEM team and confirmed that you are correct, devices need to be GMS certified in order to be enrolled as Managed Devices in the Android Enterprise platform.  

Also, in order for devices to have Managed Profiles they need to be CTS compatible.

For more information on managing Android Enterprise devices visit the helpfile link below and search for Android Enterprise

https://www.soti.net/mc/help/v14.0/en/docindex.html 

Hope this helps!