The harp never was a "vernacular" instrument contrary to what the old wives say. And it was very much in use, albeit not in its bardic role, until the late 1700s. Its demise was a technical one- the older harps did not have the ability to adapt to the newer music which modulated keys thanks to the influence of the keyboard.Professional players had to keep up with the times to get the gig. Hence the pedal harp was invented. But that's another discussion.

Places like Maine were one destination for prisoners of all the English wars, but the Maine Scots prisoners I am thinking of fought in the "civil war between Charles and Parliament" among them "Micum McIntyre, highlander". So Cromwellian it seems.

And yes, the piping population was probably about equivalent to the harping population- as specialized instruments. The fiddle and flute became favored partly due to their relative simplicity and portability.
(There is a harp tune called "Contempt for Fiddlers"...)

Regarding blowey things, we have in New England a number of collections of fife music, probably from the military. Pennywhistles were popularized in the early 1800's. Previous to that, the flute and fife were commonly played here.

Best- Julia