Looking at Manna as an example, their whole UBI aspect relies on a centralized nonprofit; what then is even the point of the cryptocurrency aspect? What value does it add on top of just setting up some BTC-accepting charity that would send donated funds to all verified individuals equally?
Some aspects of crypto could be interesting to set up the methods and procedures of an Universal Income system. However, I think some coins are using the term as a buzz word and their proposal is closer to a passive income investment, no different from the many existing ones.
Universal Basic Income, as I see it, is the compromise of a society to ensure that all its member have some income, but it has to be independent of any investment, that is, must equalise the members of the society regardless of their economic means for investment. The use of crypto or blockchain technology in this case would be anecdotical.
In a way, Universal Health services, universal pensions and free education are a form of UBI, paid in species. It is noteworthy that societies that actually accept those items as a core function of the political system are however reluctant or plain adverse to providing the same benefit in cash.... would anyone dare to mention crypto in a political proposal?