
My understanding so far is it's actually quite a tricky target to engage. It's flying so high that even if F-22 climb to its ceiling and release an AIM-120 the balloon is at just about the edge of the missile's capability.
It would be hilarious if under all that pressure Biden ends up ordering for it to be shot down, and they have to launch a THAAD interceptor to take it out.
If would be extra hilarious if AIM-120 or THAAD is used and misses, as I doubt that's the sort of target they were designed to engage.