https://www.vox.com/future-perfect/2020/2/19/21112570/univer...
Exactly what qualifies for you may mean it does already exist on a large scale or doesn't.
Alaska's UBI program gave 1.3k this year, which I'm guessing many commenters here would say is too small to be a real UBI, but it is universal and has been going for almost 50 years