Certainly not. Any UBI policy has to be set for a universal basic standard of living in a contiguous zone of free movement. US citizens can live anywhere in the US - UBI reverses the current bubble of housing prices that is concentrating people in cities that then resist increasing density and thus just drives property values to infinity. It lets people who don't want to live there the option to move elsewhere that is much cheaper and thus lets them live off the UBI.

Trying to peg UBI to regional cost of living costs an incredible amount of money (the cost of living in the Bay Area has to be at least 10x the rural Rust Belt) and has practically no benefit (because all it means is people get the privilege of living wherever they want on redistributed money, rather than choosing to either live where they want and seek the means to afford it or living where its cheapest and costing society less in macrospect.

This is, by the way, another reason UBI is a Utopian fantasy: It’s impossible to imagine an elected government resisting the temptation to fiddle with the formula to achieve policy goals and reward constituents, just like today’s tax code.

So the homeless population in SF would mostly still be homeless? If UBI is unable to help those at the lowest rung of society, what's the point?

There would be an industry overnight that would pop up to help people migrate where cost of living is affordable on a UBI because that is an insane amount of dependable profit to be made. It would be as simple as "your first month pays the move, and every month after that is last months rent payment".

There already exist communities and retirement homes whose entire agreement with its residents is "give us your social security checks, we give you food shelter etc". If you know constant money is coming in, arranging your business around being super easy to use for that money is a very lucrative opportunity.