Rocket launches from high altitude baloons have been done: https://en.m.wikipedia.org/wiki/Rockoon https://en.m.wikipedia.org/wiki/Rockoon If you mainly care

Rocket launches from high altitude baloons have been done: https://en.m.wikipedia.org/wiki/Rockoon https://en.m.wikipedia.org/wiki/Rockoon If you mainly care about altitude as with a sounding rocket, it can help quite a bit. Also some launche loop designs have parts of the structure supported by inflatable members. And there are even plans for a rather exotic airship design that could be flown to orbit with the help of solar powered electric engines: https://en.m.wikipedia.org/wiki/JP_Aerospace https://en.m.wikipedia.org/wiki/JP_Aerospace