the overton window aka “the window of discourse” is literally about talking, and making things more acceptable by their existence in the public consciousness
the more people TALK about alternative voting mechanisms, the more likely it is for some change to occur… 1 person can’t just up and change the system overnight, but by “signalling” as you’ve dismissively called it, it makes it more likely that other people talk about it and that makes it more likely that it becomes policy
these are separate issues; i never said signalling is the end game, but it has to start there and build
if you want IRV etc to be in the same category as abortion rights and cannabis (as in majority of people think “why the fuck isn’t this done yet?” rather than “huh? what?”) then it starts with simply convincing politicians to acknowledge their support for it - heck even acknowledging it as an issue
there is literally no way to get to policy through a grassroots without it first having a few people “signalling”