Did team members actually use it to develop it?
As for development of non-VR stuff I personally didn't because I already had a fully-featured desk setup and the OS at the time was buggy enough to not want to deal with it (as every OS is years before release, not a ding on Vision Pro at all). With a good OS (which it will be upon release) and more native apps (like Termius on iPad) I definitely would though!
FWIW the iPad supports dumbed down app development through Swift Playgrounds and presumably the Vision Pro will at the very least support that if it supports all iPad apps, but that's pure speculation.