Manually upload pakages to proxy cache?

Hi everyone,

is there a way to manually upload (official, unaltered) pakages to a proxy repo?
The Nexus Repository Manager is behind a proxy which will block some of the pakages.
I can manually download and scan these pakages and for most of our repos we just use a hosted repo of the same type, upload the files into that and everything is fine.
Unfortunately I’m now trying to set up a conda proxy repo where that option is not available.
I have seen that there is an unofficial plugin and might give that a shot at some point, but I was wondering:
Is there a way to manually put the downloaded pakages into the proxy cache so Nexus doesn’t try to download them and instead just uses to cached copy?