PRs ready for review _

Can someone review this, please?

Backport of a previous PR already merged:

My PR to add s3proxy has been waiting for review since November. We’re using s3proxy at work to access a Nix binary cache hosted on an Azure storage container, so pretty useful for anyone wanting to host their own binary cache on a non-s3-compatible blobstore.

A python package, should be ready for merge.

Two PRs that may take a while to review, agree on and get merged, yet could be useful or even important to consider for 24.05.