I know how to do this via the command line but it would be nice if I could also do it using the GUI.
Unfortunately the files app 'Connect to Server...' dialogue does not include NFS as a server detail Type.
Pantheon Files does not currently have this feature. Currently, the "Connect Server" dialog only works for protocols that can be mounted using gvfs. NFS servers are often connected at start up using etc/fstab. If you are using NFS for an always on NAS for example this is probably the more convenient approach.
It may be possible to extend the functionality of "Connect Server" to do ad hoc mounting of NFS servers; I suggest you raise a wishlist bug on https://bugs.launchpad.net/pantheon-files. It is unlikely to be implemented in the next release (Loki) however.
Using the search field if one enters the path to the nfs volume and presses return/enter the nfs directory will mount to /run/user/1000/gvfs/.
An alternate option to Phil's comment is to edit .config/gtk-3.0/bookmarks
and add nfs://IP/share_path
(available nfs shares can be found with showmount -e
).
Shortcut will then be available as Pantheon files bookmark.
Tested working on elementary 6.1