I just found my favorite MS-DOS game of all time on archive[dot]org. Spin - the space shooter from Ground Up (Ground-Up) Software! https://archive.org/details/Spin1996GroundUp

A simple little early game that featured the capability of swapping out module musics. It also has hilarious sound effects! :D

I also found a 4-part collection of over 18000 Commodore amiga tunes! They're even sorted by artist name and file type! This may very well be every tune ever featured on the Amiga!
https://archive.org/details/cdrom-amiga-mods-anthology-1
https://archive.org/details/cdrom-amiga-mods-anthology-2
https://archive.org/details/cdrom-amiga-mods-anthology-3
https://archive.org/details/cdrom-amiga-mods-anthology-4