As this issue has broken containment, I'll note that there are two lists of signatures.

1. An expression of solidarity with the #WikiWorkersUnited union of current and former staff of the #WikimediaFoundation. Anyone who considers themselves a member or supporter of the #Wikimedia community is welcome to sign this. Over 500 signatures now! https://meta.wikimedia.org/wiki/Wiki_Workers_United#Solidarity

2. A commitment by English #Wikipedia editors to participate in collective solidarity action (such as an editorial strike), if called upon by the union. The effectiveness of this commitment lies in its threat to withhold hundreds of hours of volunteer labour, but it is open to anyone who has edited Wikipedia or another Wikimedia project, whether you have made ten edits or hundreds of thousands. Over 400 signatures now, representing over seven million edits. https://en.wikipedia.org/wiki/Wikipedia:Wiki_Workers_United_solidarity#Signatures