That looks like a very cool option and effort. Like the Chinese balloons that overflew the US in the last (few?) years, it would likely be challenging to shoot down. Otoh, it might cause some diplomatic disagreements about overflight.
There are a number of competing theories in international law, with varying
criteria, to delineate the upper limit delineating airspace versus outer
space. This debate is unsettled. [0]
There may also be some technical challenges having to do with beamforming rf to the vehicle. Starshield like Starlink has the predictability of orbital vehicles for tracking. It would be interesting to understand how a ground station focuses on the solar glider.0. https://opil.ouplaw.com/display/10.1093/law:epil/97801992316...
Found those balloons very strange, hope they were up to something nice