I don't believe so. You *must* login to be able to get to the video wall.
I'm not sure what country you are in, but many countries have enacted privacy laws that require you to keep an audit log of who viewed cameras and video footage when. Meraki keeps a record of this for you, and this requires that people must login to be able to use the cameras.
No, but is your problem getting the initial link to the video wall, or getting a timestamped link to the video wall?
Depending on how many video walls you have....the video wall links take the same "timestamp" parameter as an individual camera, so you could manually create your own list of links to your video walls and then generate timestamped links programmatically by just adding the timestamps as follows
The API gives an example of linking to a camera as such