FTP is not one hour power. That's just a convenient way to think about it.
There is a trainerroad forum where they are running an unofficial ftp challenge - ride your ftp for an hour. There is a workout that is just one interval at ftp for an hour. Many people have done it. Who knows if they are sandbagging on the ftp number or not?
https://forum.trainerroad.com/t/the-...enge/12430/113