When there is a new post to the SO blog, it's featured on every site in the Feature box on the top-right of the sidebar, in the Blog section. Only posts from the main blog show up here automatically (though I believe site moderators can manually pin blog posts there if they want.)
Below that, though, in the Featured On Meta section, a combination of featured posts from meta.SE and meta.site.se appears together.
Is there a way to get new posts from the per-site blogs to show up here as well?
I see some older questions that indicate that new posts used to be indicated in the header bar, e.g.
Can a new official blog post also be announced on sites with their own blogs?
and
but those links are no longer present, so that notification doesn't happen anymore.