It depends on so many factors. Are you actually employees or contractors? Do they pay you from a subsidiary registered in your country? I've somewhat seriously

It depends on so many factors. Are you actually employees or contractors? Do they pay you from a subsidiary registered in your country? I've somewhat seriously looked into this a while ago and my main takeaway would be: a) contractors can't unionize and b) you can unionize locally, as long as you get signatures from X% of the employees in your country. Also, and I can't stress this enough, reach out to some already established union in your own area and ask for advice. You're gonna find out some things that are not easily googleable.