I either know a poor person (it helps not to insulate yourself from them) or donate to a direct charity. The most famous of these is GiveDirectly but there are others.
It scales because there is by definition no overhead, accounting, or infrastructure
Give Directly does have overhead. $2 out of every $10 per their website. You can choose not to support their overhead, but others must to make it possible.
It scales because there is by definition no overhead, accounting, or infrastructure