In article you write:
https://50skyshades.com/news/business-aviation/bliss-jet-to-launch-laguardia-to-london-private-jet-service-in-january

This looks like the next dead cert failure.

This looks like vapourware. It says the New York end of the flights
will be at the Marine Air Terminal at LaGuardia airport, correctly
noting that it's considerably closer to midtown Manhattan than either
JFK or Newark.

But LaGuardia is a domestic airport. It has no customs or immigration
facilities and its only international flights are from Canada, where
flights are precleared. It seems rather unlikely that the US would set
up a preclearance station at Stansted.