quick question?
can you taxi and hypersonic at the same time?

If the character is also a flyer, yes.

And keep in mind you still follow the normal rules for taxi: you have to start adjacent to the (non-flying) (friendly) figure being taxi-ed, and they only get dropped off at the end of your movement (not 1/2 way through).

so the pasenger is actually off the board during the HSS Action so no Enhanced HS fly-bys.