@TestUser, Thanks for posting in Q&A. Based on my researching, I find currently Remote help only supports for the following platforms and devices. For Android, it only supports for Android Enterprise Dedicated (Samsung and Zebra devices). From your description, our device is Android Enterprise fully managed. Therefore, it is not supported yet.
https://learn.microsoft.com/en-us/mem/intune/fundamentals/remote-help
For the remote via TeamViewer, I find the supported devices are as below. Android Enterprise corporate-owned devices are not supported yet.
https://learn.microsoft.com/en-us/mem/intune/remote-actions/teamviewer-support
So I think this is the reason you are unable to connect via TeamViewer.
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