These are diatonic scale (used often for instruments like the Appalachian Dulcimer), and typically tuned to the key of G or D.
The McNally StrumStick is another version of this kind of instrument.
That video linked by the OP is another UU member here Barbablanca who participates regularly in the weekly UU Seasons challenges.
Seagull came out with that Merlin series about 5-6 yrs ago IIRC.