I don’t see how allowing users to at least review the settings they have made could be considered un-Material. Yes, a URL might be technical, but they had to supply it in the past in order to sync to that URL to begin with
If anything it would be un-Material to not allow a user to see the info they provided in the past again.
Now you’d have to maintain a separate list outside of the app of which account name is connected to which server.
Within the current layout I’d say at the top of the settings of the account would be the most suitable location. It could be nothing more than static text if you don’t want to provide a way to change it. There’s a risk you’d need to cut the URL and continue displaying it on a second line, but the settings screen is not something you stare at often nor for a long time. It maybe being a bit less pretty but I’d say actually having the info is more important than that.
I know they are different protocols, but presumably, one app is not fundamentally restricted to one, is it?
I think such an app should not be called DAVdroid because that would confuse users (like me before I investigated the differences).
It could be good t have an Export (or Backup) button, to be able to save existing subscritions. At the moment, we can’t even select subscriptions address to be able to save them to a file. In case it is a shared calendar, we have to ask ics address again.