Sure, a world without money would be best, but it´s babysteps. Establishing socialism will always be preferable, but the thing is that UBI can pass under capitalism. If that UBI than translates to an apartment+food, the new status quo would be that everyone deserves housing+food. If it´s enough for a tent+food even, then it still acnowleges a persons fundamental right to exist. A very low bar admittedly, but lierals are that low. At least it will make it easy to frame it that way, and the positive impact the UBI would have could make expanding it/other social ideas a very popular stance.

Even a shitty, unconditional, UBI could be a good basis to build on. Now I don´t belive in reform to archive socialism, but a UBI that can get expanded through pupular support can be an incredible tool to increase labor power. It can take away the power of the bosses to starve you to death, but unlike with the other regulations, a UBI would be way harder to go back on. It would fail the moment it gets means tested though.