Remotely access a friend's files over internet (natively + not screen sharing) I am trying to help a friend organize his computer remotely over the internet. Screen sharing through macOS Messages is far too laggy to be efficient. I've been searching and reading about macOS's native remote file sharing options (File Sharing, Remote Login, Remote Management, Apple Remote Desktop, etc), but I can't for the life of me figure it all out or quite understand how it all works.

Is it possible to set up his computer so that I can remotely log into it from my own computer over the internet, through Finder, and organize his files for him, using a native macOS feature/protocol?

We are both running the latest version of High Sierra and running MacBook Pros.

EDIT: Well I've determined that the answer is no, there is no way to access my friend's files over the internet using a mounted disk in Finder, as you might over a local Wi-Fi network. The alternative is some deep Terminal usage and router set-up, which is a bit more than I can devote my time to, but I've marked it as the solution, as it does answer my question.
I would highly recommend the Team Viewer app.

Have been using it for years now to help some people over in Europe.

https://www.teamviewer.us/

It is free for personal uses...

Of course both sides have to install it