Interesting question; I'd never bothered because I tend to focus on a few albums at a time and I just keep them locally. Waiting a second or two when I want to listen to an album I haven't listened to in a while is no big deal for me. But it turns out git annex makes it easy to do this:

https://git-annex.branchable.com/git-annex-inprogress/

This makes it even more compelling to try out...

I do wonder what happens with the temp file when the full file is loaded. The quick and dirty way that most people do it is to simply delete/move the temp file as completion, but of course that interrupts the media player as the file is now “missing”. I feel like I’m going to find out shortly when I research or test...