You can add mobile extensions and set them as a default landingpage for the mobile app.
But mobile extensions only allow HTTP/HTTPS URLs, so you can set only websites as landingpages. But if a want to set a special blog overview/entry as a default startpage, it is not possible.
You can make this easily possible, when you would allow IBMSCP protocol in the mobile extensions:
With these links, you could easily configure a blog entry as a default startpage