Linux

I'm not aware of general Linux specific tools for this (game specific ones do exist). However:

• Vortex does work on Linux: https://linuxvox.com/blog/vortex-mod-manager-linux/
• So does Curseforge: https://linuxvox.com/blog/how-to-install-curseforge-on-linux/

They both work by you running them in wine and pointing them to the game files created by Steam (or Gog or any windows game installed via Wine or Proton) in the Linux filesystem (e.g. /home/yourname/.steam/steamapps/common/game) instead of windows filesystem (e.g. C:\program files\game)

Modloaders with "bootstrap" fixes will also work; they just have to be installed and run in the same proton/wine prefix as the game. I.e. if you install Cyberpunk 2077 via steam, the bootstrap type mods need to be installed into the game folder or fake-windows file system that Proton makes for the game. It even has it's own "drive C" folder for the rare times you need 3rd party tools. You also put tools into the game folder as you would on windows. If it has it's own custom exe you can tell wine/proton to run that instead of the game or even before the game in the same prefix.

I mod games extensively on Linux; they work just as they do in Windows. I've played heavily modded Cyperpunk 2077 to completion (all the mod tools work via proton - that takes a little tweaking to get working but is doable - and many mods you just drop into specific sub folders; I played with about 50 mods and I didn't find a single one that didn't work on Linux specifically), Stardew Valley, Rimworld and Minecraft for example of bredth. Stardew, Rimworld and Minecraft even have linux specific tools to help.

This is less a case of games run via Linux not being moddable, and more that it has it's own learning curve (in the same way modding on Windows has a learning curve). Once you understand how the linux filesystem and how proton/wine work, the world is your oyster. Protontricks and Winetricks are not just useful for getting games running or tweaking them, they're a modders best friend.