The entire thing is best viewed as a super-short-term credit basis between all participants. At no point is the financial system in a state of absolute settlement. It is continual flux. Best you can get is scoped, relative settlement with assumptions. DTCC is the most fundamental source of truth, but this is after the fact and not very useful when one needs to make an immediate decision.
Yeah, but settlement happens EOD not on each transaction (as the orders fill). As long as we're talking about trades not on margin then Robinhood should already have the requisite assets for clearing readily available.
