Looks like you are correct. I don't think I could find most if not any of the leaders from the leader pass. Including Sejong. That's incredibly disappointing. Looking through the contents of the dlc from a proton install I'm not seeing anything that would prevent someone from just using it on Linux other than editing the paths. I'll experiment some. Maybe I'm naive and there's a reason why no one else has done it.

Edit: proton has come so far that maybe Linux peeps just opt to use that for civ6. Especially since the Linux build might be a tad buggy? At least for me it's definitely had issues.

Edit2: Ha. It works. That's wild that they would just lazily not repack it..

• just copy the windows dlc packs over,

• copy DLC/_/Platforms/Windows -> DLC/_/Platforms/Linux

• Then inside the platform Linux dir

find . -type f -name '*.modinfo' -print0 |
    xargs -0 sed -i 's#Platforms/Windows#Platforms/Linux#g'

Some don't seem to show up in game still so I'll experiment more this weekend if I get time and throw together a bash script that downloads all the windows depots and patches them.

Edit3: for the ones not working it might be due to case sensitive file system. They use audio when looking for Audio