These are a brilliant idea.
I'd love to see them in pubs, toilets in student unions, etc.
But can I make one small suggestion re. this activism? I'm not entirely sure that they should be going in places where women are likely to be taking their children to the toilet - imagine having to explain one of those to your six year old.
(Yes, I know part of the point is that those six year olds will be confronted with be-penised individuals if the self-ID mob get their way, but I don't think the optics look good if we're rushing around sticking them up all over the place without any thought for who might see them - Caesar's wife and all that.)