However, those assuming it will never be sold or even legal to be sold may not be aware there already exist astronomically expensive, completely impractical, quite unsafe, track-only hypercars which are not legal to drive on any street.

As for the technical legality of the 'flying' features ask your LLM about: the Ground-Effect & "Sustained Flight" Jurisdictional Boundary in FAA / NHTSA regs, Off-Road Track-Only exemptions from Federal Motor Vehicle Safety Standards, and PHMSA / DOT-SP (Special Permit) authorization for consumer COPV pressure vessels. Making the "hopping" version for sale is a wildly impractical marketing stunt but they can probably do it, although it'll cost far more and ship much later than whatever they promise and will sell at most a few dozen.