Clone ubuntu apt repos

Is it possible use nexus not as just proxy, but like full standalone repos of ubuntu, or debian for example?
If it is, how to do it?

You can with Apt Hosted Repositories.

looks like the solution for only own repositories.
But I need to clone “us.archive.ubuntu. com/ubuntu/” for example

If it’s possible, could you give me the steps how to do it by using nexus please?

Ah sorry I misread your comment previously - you’d want to take a look at the Proxy section of the same document.

So after following these steps I will get a full mirror clone of archive.ubuntu. com/ubuntu/ bionic repositories, which will let use it as primary ubuntu repositiories without internet?

No, Nexus does not proactively replicate contents it acts as an intelligent proxy of the remote content. If you were to pull the entire content of the remote repository through Nexus then it would have a copy that could be used offline.

So there is no way to pull the etrire content in couple of clicks or commands, right?