Given Adobe's history with supporting native APIs, the answer is almost certainly no. We're still waiting for a way to create native alerts and dialogs from within AIR. There is no way they would give us the ability to create keyboards and widgets before something as simple as that.
It would be possible to do via an ANE, but it would be pointless since it would have to be done entirely in Objective-C or Swift anyway.
It's also worth noting that Android has supported third-party keyboards and widgets since the beginning. Adobe has never once made a move toward supporting the creation of these or given any indication that they intended to. Such things are not within the primary scope of their AIR project and never have been.