It’s best to unionize everyone as much as possible, and indeed there are unions for essentially every job, so that everyone’s pay and working conditions can improve as much as possible. Everyone deserves a shorter working week.

I saw another comment where I think you said you work in tech, so I will paste this:

There is a tech union :) Unions and pro-union movements have been growing a lot in major tech companies in recent years and they have already had significant achievements in improving workers’ conditions. If you would like to join don’t hesitate to check out CODE-CWA and remember the most important thing is to start building support for unions among your coworkers!