All Microsoft Teams IP Phones are managed and updated through the Teams Admin Center (admin.teams.microsoft.com).
Each Phones settings in the teams admin center has custom fields for organisations to use: Organization asset tag, Notes.
You can see them if you click into a specific phone and details you can see them. However, there is no obvious way to edit them from this screen.
You actually edit them by going back to the main device list, selecting/ticking a device and then selecting edit:
Unfortunately, at the moment there is no ability to search or filter the main phone list by Organization asset tag, Notes, but you can by device name which you can also customise.
So if you set your device name in a specific format you can use that to filter your devices and patch a select floor of devices at a time.
At the time of writing, there is no API or PowerShell access to manage devices.