WashedAnus

The Industrial Workers of the World (IWW) does external organizing, but it's not quite what you're talking about, I think.

The structure of it is that there is a branch in the local area (in Wisconsin, there are branches in Milwaukee and Madison, although I don't know how active they are) which workers trying to organize their workplace reach out to, and they provide External Organizers (EO's) to coach the workers on how to systematically organize their workplace. They meet up, talk about the structure of the workplace, set goals, and then meet regularly to help push the organizing along.

There is another tactic called salting, where a union will get some of their members hired at an employer they are targeting to start the process.

Other unions use these tactics as well, I'm just less familiar with them as they're less radical. To be an EO, you have to go through some training and gain some experience at your own workplace or shadowing other EO's.

If you're kinda very much a communist, the IWW can be a good organization to be a part of. It very much attracts anarchists and syndicalists more than Marxists, but we're here too, and it's generally not a big deal if you don't make it a big deal. Other organizations also do workplace organizing. I am aware of workplace organizing campaigns by CPUSA and even DSA.

Hope this helps!