You can work with objects from a console by creating a pad. Here it's called site for consistency with what you find in the templates:
from lektor.project import Project
project = Project.discover()
env = project.make_env()
site = env.new_pad()
You can get blog posts by:
>>> list(site.get('/articles').children.limit(3))
[<Page model='blog-post' path='/articles/psycopg-284-released'>,
<Page model='blog-post' path='/articles/psycopg-283-released'>,
<Page model='blog-post' path='/articles/psycopg-281-282-released'>]