GPS is in the syllabus and should be taught both theory and practice. Unfortunately the syllabus is a rather poor document and quantifies very little. Whilst no radio/nav is in the LAPL or NPPL syllabus, if the student were to learn on an aircraft where gps is an integrated part of the aircraft systems you could not get away without teaching how to use it.
We have a requirement to teach traditional navigation but it is up to the instructor to integrate that with the use of modern equipment. Unlike the RAF who now have Grob trainers with an integrated glass cockpit, producing a syllabus to match the aircraft is relatively easy but in the civil World training takes place on a variety of different aircraft fitted with an equally diverse range of equipment.
It is a challenge for instructors to teach conventional skills and to incorporate modern equipment. Sky Demon was the original topic and one must accept that this is a portable aid and is not built into most aircraft, as such it is not the primary navigation aid.