Use Profile Manager (or other methods?) for Network Mounts/Favorites
The files which store Finder favorites and server lists are located in

~/Library/Application Support/com.apple.sharedfilelist


The file formats in this directory are sfl2 which is ultimately a form of BookmarkData internally, stored within the plist format encoded as base64. The sfl2 format cannot be modified with current command line tools on macOS 10.14+, although in earlier versions of macOS this was possible using the command line program sfltool.

However if you copy these files from an account already set up with your desired favorites e.g from another machine (this can be done once and repeated on many devices) then kill the process sharedfilelistd the list(s) update within Finder.

The file which stores the server list is called com.apple.LSSharedFileList.FavoriteServers.sfl2 and the sidebar list is com.apple.LSSharedFileList.FavoriteItems.sfl2

I have personally tested this with the server list, however I'm unsure of the implications of updating the sidebar list without user account path conflicts.