Following: https://developer.cisco.com/meraki/build/deep-links/ we're creating deep links directly to a device e.g https://api.meraki.com/manage/dashboard/show?mac=e0:55:3d:f4:39:17 (as DevNet Sandbox device)
If the user is not already logged in, then they are shown a login page, but this appears to be visually broken and would (rightly) discourage a user from entering their credentials.