You know that you can lookup the url of a ressource by opening the 3-dots menu behind e.g. a calendar and choosing properties? That’s not exactly what you asking for but a workaround. I would assume that the base url is usually the part in front of the user name.
Custom home set
Is it possible to set a custom path/home set? I havent set up my server to work with automatic path detection, and would like to view other users’ public calendars or a root calendar.
Yes, just use the home set URL as base URL. See https://www.davdroid.com/manual/#c19 for details.