Thank you for your reply Sara_Cummings!
It is the same three news templates that we push to all sites, yes. For the intranet sites we also have a few extra templates. A subset of the intranet sites are used as dedicated news sites for corporate communications, but we also allow and encourage people to use the news functionality on other sites, including team sites. With this comes a requirement from the organization to provide branded news templates on all sites.
So, the 40k sites include all modern Sharepoint sites ever created in the background by one of the Microsoft 365 products. Most of them have probably never been touched and will never have any news posted on them, but we really don't have a way to know which ones will. That's where the thought originated that it would be great if we could push the news templates globally, making them appear on all sites just like the default Microsoft provided ones.