targeted boycotts seem to prove more effective in the United States

Targeted boycotts have never removed a party from power. There has never been a general strike in the US either. But general strikes in other countries have been effective. I can't think of anywhere that boycotts have accomplished much unless they've been accompanied by mass action.

I can’t be sure, having never seen general strikes manifest or boycotts that lasted.

Look outside the US. US labor law has been rigged to prevent unions having any power, and the US has always sucked at worker solidarity (except for some sporadic outbreaks of rebellion in the early 20th century before the IWW was suppressed).

Boycotts also rule out those of us who live in poverty who can’t afford to have opinions.

The swadeshi movement organized by Gandhi largely involved poor people resisting exploitation by state monopolies. It was pretty effective, though the boycott was only one part of a much broader strategy. The same could be said about the Montgomery bus boycott, though the goals of the SCLC were narrower than regime change (when King tried broadening it to something that looked a bit more social-democatic and applicable to all working Americans, he caught a bullet). Same thing happened to Fred Hampton when he proved effective at building alliances that defied the prevailing racially based divide-and-rule scheme. The elite really doesn't want us showing solidarity.