LXD 5.0 New File Transfer API

In The plan for LXD 5.0 LTS video, a new file transfer API is mentioned. Could someone be willing to link some resources so I read into the advantages of the new API, as well as how to use it?

Some advantages were discussed in the release thread here.

The docs for the API itself are here

as well as how to use it?

With lxc do something or the actual API?