The soundtracks for the base game and Echoes of Auriga were uploaded on the forums here previously, but the music from the other expansions is still missing.

VGMdb: https://vgmdb.net/album/83725
Bandcamp: https://endlesslegenddefinitiveedition.bandcamp.com/album/endless-legend-definitive-edition-soundtrack

I'd very much appreciate an upload. :)

I second this.