You have to use Apple Business manager or Apple Configurator with Intune to enroll. This way the Devices are treated corporate.
https://learn.microsoft.com/en-us/mem/intune/enrollment/ios-enroll
Other way is to add serial number manually.
https://learn.microsoft.com/en-us/mem/intune/enrollment/corporate-identifiers-add
The difference with corporate device is as you said inventory for apps and other things it can do is full phone numbers and if you use Apple Business manager, you also get device into "Supervised" state, which gives you deeper control of the device.