I can think of one animal that already evolved something along the lines.
Image from Pbs.
Some spiders use spider silk for flying in the air. They just weave silk in the wind until it’s long enough that the air currents drag the silk with enough force that the spiders are dragged along and fly long distances.
Most of such journeys are only for a few meters but there have been reports from sailors that spotted spiders blown by jet stream even 1600 km away from land. Ballooning this way spiders have also been collected from air samples up to 5 km above sea level.
There are also sea organisms that evolved balloon-like ways of floating in the water.
Portuguese man o’war, which is a colony of hydrozoans, composed of many individuals. I suppose, that hypothetically if they evolved filling this balloon, that they already have, with something lighter than air. If they made this balloon bigger. If they also evolved surviving dehydration outside water. Most importantly they would need a reason to balloon to the air, like maybe for some sort of food, maybe air plankton. Hypothetically it could happen in some distant future. They already evolved the right shape for this to happen but there are still many missing steps and the reason for taking off from water to the air.
Image from Wikipedia.
I’ve always been very fascinated by how gliding fish evolved. Flying fish glide in the air to escape predators. Maybe, just maybe ballooning organisms will evolve in some distant future too.