How to make a functional legless hummingbird?

The reduction in their legs is already a clear trend today, with them being vestigausi organs in several species.

For a project that I have been developing with my girlfriend, I was thinking about a species that would have lost them for good. This new species would never land, even sleeping in the skies, having also evolved an ability similar to dolphins and crocodiles to sleep with a brain still active, always remaining alert.

Is my idea functional? If not, how would you try to adapt it to work? (English is not my native language, so forgive me if it is poorly written or strange)