So if it were legally considered to be a PPL(H) heli, one could do the bigger part of the pesky 180(?) h PIC time requirement for a CPL in a very cost effective way.
Probably not if your NAA insists that the time is spent in a helicopter with a type certificate. Check closely.
and acquire a rating for a single seat heli
In this case you cannot as there is no "type" as in Type Certificate. Its an ultralight.