Bulk configuration of Favorites/Speed Dials for common area phones

We're about to deploy a large number of common area phones throughout our building for use in utility spaces and next to the stairs, each with its own 365 Shared Device user account and phone number. We would like to set their Favorites/Speed dials with contacts such as the Front Desk, the First Aid call queue, and the IT Service Centre. 

Is there any way to do this remotely as a bulk process, or does it have to be done individually? Is there a template, a policy, or some sort of scripting process that we could utilise? If nothing else, is there a way to automate signing in to 30-40 Teams accounts, setting each of their Favorites, and then log out again?

This seems like a pretty standard requirement for common area phones, but I haven't found any clear documentation on carrying this out.