I think other pipes may have a conical bore too. But Highland pipes are a fantastically optimized piece of woodwork, right at the edge of what is technically feasible (which is why they go wrong so often).

I meant that about making pipes with a pocket knife - that is exactly what you are supposed to be able to do with Hungarian and Black Sea pipes (though makers today cheat and use machinery). Exotic materials from far away are also common - a modern version being the Black Sea pipe, with a double chanter whose (now) traditional timber is umbrella handles. But that kind of peasant tradition died out in Britain and Ireland centuries ago. Pete Stewart has an argument that the standard type of bagpipe in both Scotland and England until the end of the 18th century was a variant of what we now call the "border pipe" - not necessarily African blackwood but nearly as hard to make as a Highland pipe, and nothing like the Eastern European ones:

http://elearning.thepipingcentre.co.uk/wp-content/uploads/2013/03/PT38_LowlandPipes.pdf

Whistles are related to reeded pipes in some places, particularly Anatolia, where the fingering systems of flutes and parallel-bore oboes are the same. But flutes have had an autonomous evolution as well. There are descriptions of six-hole pipes in Diderot's Encyclopédie which are pretty much like a modern whistle except made of wood, so the English inventors of the tin whistle didn't need to refer to bagpipe designs at all.

Anyway. Back to dulcimers. My bet is that they brought the hackbrett/scheitholt idiom and repertoire with them. Whatever that was. It must be documented for some places in Europe. It usually takes quite a while for an imported instrument to go native and acquire a new repertoire and technique.