Which cryptocurrency lets me do a chargeback?
You don't necessarily need to use a publicly available cryptocurrency that exists in the wild today. If an organization was motivated enough and thought it was a good idea, they could simply launch their own private blockchain on their own hardware that they control. With your own blockchain on your own hardware you could still reap the benefits of decentralized compute power, and build your own smart contracts system that can broker chargebacks. The barrier to entry for an endeavor like this is the lowest its ever been too, you can even spin up a managed blockchain on AWS these days.