I am unable to install a watchOS 2 WatchKit app due to an application-identifier entitlement. This happened after turning on App Groups in the Capabilities tab.
Full
With MacOS Catalina, your iPhone will be displayed in the 'Locations' sidebar of Finder windows (as long as you've got the Finder preferences set up to show external devices) - you can then access the files via the 'Files' option which is available from the bar near the top of the window, just below the title (in my case I had to click the '>' at the right).