Inhaled vax typically don't work well compared to injected vax. FluMist does not work as well as injected vax. NasoVax does not work as well as injected vax. CanSino is not an effective vax to begin with, only 65%. It would never be approved in the west.
J&J got an EUA from the FDA with efficacy of 66.3%. I guess the 0.6% advantage it has over CanSino must have been crucial.