Just read an article posted here that the V-22 is now in development of weapons systems to include a chin gun and also possibly the 30mm cannon. How is that for your sea-based variant? The one thing the V will never have is the stealthy noise attitude of the A-10 along with its maneuverability and the ability to loiter without refueling. IN GW1, the Iraqi soldiers gave it the name of Silent Death because they just could not hear it coming until it was way too late. In joint operations, both will be employed to devastating effects if the up armed V comes to pass which I think it will.
The Marines here qualify for jump training yearly with the V-22. In “helo” mode it is as noisy as Huey, but in “airplane” mode it is surprising quite. Especially if it is coming at you head on.
I know the V-22 is carrier capable and it has VTOL/VSTOL capabilities, not sure if it could provide rapid close air support like the Harrier. They may be able to make it a mini AC-130. The problem is the Marines and other NATO nations use ships specifically designed for “jump jets” .