But it’s got only 10,000 users. But we know more than 100k users on twitter posted their npub either in a tweet or their bio.
Discussion
How do you know there are 100k npubs on twitter?
Whoever has such a tool at their disposal could trivially map npub to twitter accounts?
Maybe you could use the Twitter API to search profiles for npub keys to get a rough idea?
This report on #twittermigration http://www.deweysquare.com/wp-content/uploads/2023/03/DSG-Snapshot-of-the-Twitter-Migration-March-2023.pdf
I don’t see the 100,000 number for nostr. Maybe you misread for mastodon?
On pg. 9 I see a few thousand npubs in twtr bio.
On pg. 10 I see a few thousand migration to nostr post counts.
Report states less than 10,000 total npub count.