UNICEF's world food program operates a quasi-UBI system with a private Ethereum fork for refugee camp. They link crypro accounts to each refugee's Iris, and are given money each week or month to use at their camp grocery store. They simple scan their eye to check out.
It's not crypto in the traditional sense as it's a specific application of a singular entity but it fits the bill. For a decentralized UBI system, I do think this would be possible but under current initiatives will be unsuccessful.
The crypro-centric UBI I envision is a Decentralized Autonomous Organization with a legitimate mechanism for creating profit where a certain % of profits are redistributed to every participant in the DAO. There of course would need to be some metrics of human participation to prove that botters aren't dominating the reward pool. I'm uncertain how they could make that work. RaiBlocks kept good authenticity of their faucet with the help of an audio catpcha.
IMO a better idea would be to compete with Patreon: subsidize non-traditional work so that people can escape the 9-to-5 nonsense. But even then, I suspect that creating a new cryptocurrency would be counter-productive; you don't need to shoe-horn a new coin into every little thing.
Crypto would be notoriously bad for a Patreon alternative because you can't offer recurring payments in the same manner you can with credit cards.