Honestly the most complete source of high res music is private trackers like redacted. You can download all the stuff from qobuz and bandcamp, every CD rip you can think of in bit perfect quality of and even very good vinyl rips. You basically can download any version ever released from any album.
It’s a rather standard feature. Hardware and software have to be built/configured right for it to work well. That’s what Valve did. I don’t think there is any special sauce involved software wise.
If you use osmand for navigation you can use that to view your tracks, too.
Nope. They are similar, but not the same: Comparison
What’s your hoster?