Hello @Henk1961,
The Organization > Configure > Inventory tracks deployed and available devices only. Antennas, SFPs, and power supplies are not tracked using the Inventory page as they are accessories, not devices.
You can get the information about power supplies for all devices Organization-wide by using this API call: https://developer.cisco.com/meraki/api-v1/get-organization-devices-power-modules-statuses-by-device/. From Dashboard you can find the information from the "Power" tab on the Security & SD-WAN > Monitor > Appliance status page (for MXs, if applicable ) or from the Switching > Monitor > Switches page, then selecting a switch from the list. Switch models without power supplies will also have the "Power" tab, so it may take a lot of manual effort to validate information from the UI.
Unfortunately there are no API calls for SFPs or antennas. SFP information can be seen on a per port basis on switch ports, as long as the SFP provides that information to the switch. Additionally, this information is only available on switches. MXs do not provide that information on Dashboard.
Antennas on the other hand will most likely not show their information on Dashboard. Some antenna models are auto-detected by a connected AP and will automatically appear in Dashboard (specifically the antenna models mentioned here for the CW9163E: https://documentation.meraki.com/MR/Other_Topics/Frequently_Asked_Questions_regarding_Cisco_Meraki_A...). Other antennas would need to be physically inspected to determine what model is connected. You could then use the "Notes" section on the AP to keep track of what is connected and use this API call: https://developer.cisco.com/meraki/api-v1/get-network-devices/ to obtain all devices in a network. If a note is added to the device, a field for "Notes" will be returned by the API call.
I would also recommend using the "Give your feedback" button on the lower right corner of any Dashboard page to request either an accessory inventory or accessories be added to the existing inventory on Dashboard.
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