The API does not yet expose the accelerometer or motion sensor data from CW91x access points. It is not documented in any of the current official API endpoints.
If the AP reports movement as an event (like "Device Movement Detected"), it could be captured by webhooks.
If you wish, you can submit a feature request directly from the Meraki Dashboard.
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
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