Giving UBI to only 500 people, in a city of millions, is not a valid test of UBI.
Give it to the entire city, and publicly announce it a year ahead of time. That's a valid test of UBI. And it will fail spectacularly, when landlords jack up rent in response.
UBI is necessary, but not enough. We still have to fix the landlord problem, or UBI will be nothing more than yet another subsidy for the landed gentry.