Big +1 for GiveDirectly.

Do you think that a basic income could act as a disincentive to work at all?

Compared to the current system of overlapping means-tested benefits resulting in welfare cliffs, basic income would absolutely incent work. That’s because it ensures each incremental dollar earned increases take-home pay. See this chart from FiveThirtyEight’s basic income profile for a (limited) view into welfare cliffs.

would a land value tax not be regressive on commercial land?

Farmers and even homeowners have a relatively small portion of the US’s valuable land. Most of it is owned by corporations or wealthy urban landowners like the president-elect. A basic income finance by land value tax essentially says: if you’re using more than your equal share of land, you have to pay your fellow citizens for that privilege.