The ability to close & redirect to other SE site only allows redirection to stellar.meta. Shouldn't it allow the full suite (stackoverflow, superuser etc)?
Not while the site is in beta.
The migration list for beta sites is always just between the main site and its meta. It is only after graduation that the list may become populated with other common targets.
There are related posts on the main meta regarding this, e.g.
What is the reasoning behind restricting the number of migration paths?
Allow Beta sites to migrate questions to relevant sites