How to update index offline in nexus 3.28?

I downloaded the offline cable from the central reference warehouse( Central Repository: .index ), as shown in the figure below:
How can I import it directly into nexus? First of all, I use nexus version 3.28.1-01.

In addition, how can pypi and NPM dependency packages be imported offline to nexus 3.28.01?seek help.

Who can give me a hand?

I don’t believe nexus repository manager 3 supports updating from a remote index like that (someone will surely correct me if I am mistaken). Nexus repository manager 3 proxies can only be searched for items they have already proxied. In other words, you must download something from the proxy before it can be searched for.

What I understand is that nexus2 supports importing Maven dependency packages from the central warehouse offline. Does nexus2 support importing NPM and pypi dependency packages offline? If so, how to operate?
Looking forward to your reply!Thanks!