Noone claims the content data of push notifications is significant. But the data connected to the push ID is: A Apple/Google-ID, and everything in it.
While researching for our article, I sent Signal repeated press inquiries. Among my questions was:
"Of all user accounts that Signal had to hand over data to authorities since 2020, how many datasets contained push tokens?"
I still don't have an answer. I still would appreciate one. I'm sure, many other users, too.