libgutenprintui2-dev binary package in Ubuntu Focal amd64

 This package contains the header files for the libgutenprintui
 library, along with a static version of libgutenprintui.
 libgutenprintui contains GTK+ widgets which may be used for print
 dialogs etc. for use with libgutenprint.
 .
 Install this package if you wish to develop packages that use
 libgutenprintui.
 .
 Gutenprint is the print facility for the GIMP, and in addition a
 suite of drivers that may be used with common UNIX spooling systems
 using GhostScript or CUPS. These drivers provide printing quality
 for UNIX/Linux on a par with proprietary vendor-supplied drivers in
 many cases, and can be used for many of the most demanding printing
 tasks. Gutenprint was formerly known as Gimp-Print.

Source package