Unionization doesn't mean removing your value proposition from the equation. There are still different title tiers with different pay, and variance in pay within a given band. I would hope a tech worker union is less tenure-oriented than a union like the UAW but I acknowledge that is tricky to implement and not guaranteed.

If you are vastly more productive than coworkers in the same title band and wish to capture more of that surplus value, you should look to change employers, found a company, or become an independent consultant. Those are the available options with or without unions.