M365 Defender - Network Discovery

Hey David_Caddick, really appreciate the insight and feedback!

When your refer to a needed dynamic list of live agents, that can be identified by going into the "device inventory" then filtering by "onboarding status = onbarded" (has MDE) then looking at last seen attribute or health state  (see more here Device discovery overview | Microsoft Docs \ View and organize the Microsoft Defender for Endpoint devices list | Microsoft Docs).
The goal, which was built of course for large organizations, is to reduce the need in keeping and maintaining a list of scanning agents rather having Microsoft provide this as an out of the box service which you do not need to manage given MDE being widely deployed.

On renaming a device - that is currently not possible, that said we do track this a a top customer ask and are looking forward to make that happen 🙂

On offboarding devices - we are able to track devices and if a device have been offboarded we will change the entity "onboarding status" field to the right one 
If that is not the case on your tenant, mind sharing the orgid and the deviceid over email?
Yobasha@microsoft.com  

Thanks 🙂
Yossi.