As of this past week in the FreeBSD source tree for FreeBSD 16, the last of the GNU GPL licensed code from the base system has been retired.
The dialog implementation was the last piece of GNU GPL licensed software in FreeBSD's base system. The FreeBSD installer previously transitioned to using bsddialog in place of dialog and then dpv was the last user of dialog but itself since turned off and now retired.
This ticket to retire dialog was opened back in February while is now merged to the FreeBSD source tree for what will become FreeBSD 16.0.
With dialog removed, the latest FreeBSD code now retires the GNU sub-tree of the FreeBSD base system now that no more GNU code remains.
FreeBSD 16.0 is working its way toward release that is expected to happen in December 2027.