Install GE-Proton on Linux

For native Steam installations (most common):

~/.steam/steam/compatibilitytools.d/

For Flatpak Steam installations:

~/.var/app/com.valvesoftware.Steam/data/Steam/compatibilitytools.d/

Download the latest GE-Proton release: Go to the official GloriousEggroll GitHub https://github.com/GloriousEggroll/proton-ge-custom

Extract the downloaded GE-Proton10-10.tar.gz file directly into the compatibilitytools.d folder. Make sure the extracted folder (e.g., GE-ProtonX-XX) is directly inside compatibilitytools.d.

Make sure to unzip the achieved file GE-Proton10-10.tar.gz and removed the archived file after extracting all the folder contents

Restart Steam: Close and relaunch your Steam client.

In Steam go to "Compatibility" tab and choose the GE-ProtonX-XX and it will prompt you to restart the Steam again to take effect the changes.

Summary:
/.steam/root/ or /.local/share/Steam/ is the standard location for Steam's user data.

compatibilitytools.d/ is the directory within that location where custom compatibility tools are placed.

The Flatpak specific path, ~/.var/app/com.valvesoftware.Steam/data/Steam/compatibilitytools.d/, is used when Steam is installed as a Flatpak package.