In general Andrew intended that proposal to re-orient the conversation about spending priorities and service delivery.
In concrete terms, Andrew proposed a VAT, while also reorganizing existing social welfare programs, of which there are uncountable multitudes, each with highly specific eligibility requirements and screening and fraud machinery, into a more coherent, holistic delivery model that de-prioritized or eliminated eligibility.
His numbers "work" but at that scale they entail such an enormous reworking of federal and state machinery that they're in practical terms a non-starter. Cue up recent conversations about M4A, Obamacare, etc, but on an even larger scale. (disclaimer: I support the idea, but appreciate it is more conceptual value than concrete implementation.)
Right now, Fed govt takes in $3.8 trillion in revenues, mostly taxes, spends $4+ trillion, with two thirds of fiscal dollars going to human-oriented mandatory programs like social security, medicare, medicaid, various federally funded insurance programs, etc and one third going to discretionary, which itself is half military, then half everything else.
A VAT would essentially be a transaction tax that scaled to GDP, so from a model perspective, while GDP is $20T, a VAT would bring in $2T of new revenues, sufficient to begin a conversation about giving $10k/year to 200,000,000 people. In reality- who knows. A VAT would have huge implications and lots and lots of things would change.
A lot of the comments center around credit dollars that the Fed has created- basically large scale loans- to provide transitory liquidity to the financial system. Those comments misunderstand the nature of credit dollars, but IMHO they are not wrong. Credit dollars are a completely different tool than the above fiscal dollars generated from taxes. The US government has essentially infinite credit capacity.
To my eyes credit dollars are both a better and more appropriate funding source for something like UBI, particularly if UBI is tweaked to focus on the liquidity needs of children, women, and those whose current fiscal value is low relative either to future value or to the fiscal value of others. I would love Pelosi to consider that as a concrete option, the politics seem ideal for it.