probably the most directly helpful boycott is one that ensures money is denied to US companies so they are motivated to lobby and change things to protect their bottom line (as a last resort of course, and maybe not at all)

cultural boycott is more extreme and less directly important to bringing about immediate political change, but is nonetheless probably an important part of bringing about rejection of US hegemony and dominance, so it’s not a bad approach in addition to denying the US your money