my insights in Social media feel to limited :)

Yes less but not only one. I feel like we should push one format most, which in my opinion should be something physical (like offline demonstration/drawing on the ground) but we should keep 1-2 formats that not takes that much preparation (like posters and window coloring).

Yes and no. The less formats the better, but I do not think it is technically possible to agree on one format. There are too many actors involved in too many different environments.
For example, I would love to push for a offline demonstration because it causes a lot of attention with only a few people involved at the moment. It is possible to do that in Germany already, but France and Italy still have much tougher restriction.

This was exactly the outcome of the breakout room I was in, too! Totally agree - this gives us a consistent action which is more likely to be picked up by others outside our groups and result in a 'snowball effect' of people joining in if people see a consistent idea everywhere.

Also, should be simple and give v. simple and specific instructions so people know how to get involved. I.e. 'Post a picture of X. Use hashtag X.'