In backoffice I want it to work only with DE store, AT store won't be able to access

hello-world/index/index

controller Are there any solutions?

I think there you have to override the Back Office routing (to treat it for AT like it would not exist at all)

Are there any documentation instructions for overriding the backoffice route?

not that i am aware of since this is (afaik) a not so common use-case