My understanding is that since IP cameras are basically mini Linux servers, they should be able to support Profile G just like any 'normal' NVR running on a traditional box or PC. That said, I reached out to the ONVIF technical committee for comment.
Btw, I have not heard any manufacturer announce official (or planned support) for Profile G. If anyone knows of such support, please share.
Here's the answer on edge recording directly from a contact at ONVIF:
IP Camera edge storage is one of the two main use-cases covered by Profile G, the second one being NVRs. A Profile G IP Camera with edge storage will allow a client to query a list of recordings in order to configure, enable or disable them as well as build a timeline and request media streams for playback. It a bit different than a camera acting as a VMS as the Profile specification was written from the start to address IP camera edge storage use-cases.
So yes, it will cover SD card recording. It's not intended to be a VMS replacement (like Axis Camera Companion), but it will point the VMS to the SD slot as a storage location.
Thanks for the feedback guys. I wasn't so much interested in whether a camera can act as an ONVIF conformant VMS on its own but if a 3rd party VMS is Profile G Compliant and a Camera is Profile G compliant then will the VMS be able to store to and retrieve data from the camera's SD card "out-of-the box" (no integration work) as just another storage location. The answer you got from ONVIF indicates the answer to this is yes but it is not entirely clear.