Tested it out, Binance's current US stock feature is still very basic. The stocks you buy are just accounting units and can't be withdrawn since they're not in token form. So the current 'Binance US Stocks' setup is on-chain + Alpha using the ONDO solution, while direct US stock connections use US stock market makers/clearing firms + local accounting. Whether they'll completely kick out ONDO later will probably take some time to figure out, especially since ONDO has a bunch of Wall Street backing it.