@Mr Vance, Thanks for posting in Q&A. From your description, I know you want to enroll the Microsoft Entra Hybrid Joined Devices into Intune.
To enroll such devices, you can try GPO enrollment.
But as you mentioned, these devices are in pending state in Microsoft Entra ID. Based on my experience, that means the Microsoft Entra Hybrid Joined Devices may not completely succeed. You can run "dsregcmd /status" to confirm if the DomainJoined, AzureAdJoined and AzureAdPrt are all yes. If not, please follow the steps in the following link to troubleshoot:
Hope the above information can help.
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