Unfortunately 61.75 doesn't apply to an NPPL, since that is not an ICAO (i.e. internationally recognised) licence and therefore cannot be used as the basis for a piggyback FAA certificate.
Your options are probably (1) Upgrade your NPPL to an EASA PPL SEP before you go (rules changed on this recently - not as relatively straightforward as it once was) then use the 61.75 route on arrival; (2) Train for a US certificate when you get there, or; (3) Find an ultralight flight school or Club under
Part 103.
Option (3) won't get you flying "Group A" in the US though.