If we restore our Microsoft 365 / Entra ID environment into a new (recovery) tenant, will our devices automatically reconnect?
No. Restoring your directory data into a new tenant does not reconnect your physical devices to it — devices and tenants have a separate trust relationship that isn't part of a data restore.
What does the Entra ID backup restore for devices?
It creates a new device record in the recovery tenant - the device's entry in the directory - along with supported Intune configuration and device compliance policies for it.
What doesn't it restore?
Restoring a device's record is not the same as restoring its trust relationship with a tenant. It does not change which tenant a device is actually joined to, transfer its security credentials (TPM-based keys, certificates, Primary Refresh Token, Windows Hello setup), or move Intune enrollment. BitLocker recovery keys are captured in the backup, but restoring them into the new tenant isn't supported yet.
So what do we need to do to reconnect our devices?
Each device needs to be removed from the old tenant and joined and enrolled in the new tenant separately, through your own endpoint migration or reprovisioning process.