I have two problems with any UBI on a national level. 1) Milton Freidman loved the idea, and 2) it is not countercyclical to the business cycle, so it would be naturally inflationary.

Lets look at #2 more closely. If a lot of people began getting money in excess of their wages enough of them would spend it to raise employment and GDP considerably. This would drive wages up if the cause wasn't from new money creation, but good luck getting a raise from your boss when you're getting $800 / month from the government.

Remember that no UBI can be sufficient to supply everyone with everything they need to live in a modern society. That would make work entirely inflationary. The way most approach funding of a UBI is largely from existing safety net costs and taxation on upper incomes. I think our success at taxing upper income earners is testimony for what we can expect in that methodology.

This means you are on your own to provide most living expenses should you be laid off or become disabled. That $800 will suddenly appear quite insufficient and employers will become even more necessary to survival than they are now, keeping them firmly in the driver seat of the economy (see #1 above), but without the pressure of matching wages to living costs.