Apple is very clear what MDM has access to. Texts, calls, photos, apps data etc are not accessible via MDM. Even in DEP mode you need something like Apple classroom just to see the screen of the managed device.
The original question was about BYOD enrollment, I believe, which doesn't allow for any kind of access to a phone.
New self service portal portal.meraki.com provides a good view what Meraki admins can see and do from the Dashboard. This scaremongering you started is really unnecessary.