The best way to unionize is to follow what Mahatma Gandhi did: Non-cooperation movement.
It consists of two broad strategies:
1. Consumer Non-Cooperation (Boycott): Boycott of stuff sold, or given by these companies, irrespective of how attractive it is.
2. The Constructive Program (Self-Reliance): Building and supporting alternatives, even if they cost you a little bit more.
All it needs is little self-discipline and a very very tiny bit of sacrifice on daily basis.
Massive individually coordinated group actions only work is very dire circumstances which means for most everyday things they cannot be relied upon.
We are headed there.