Some days ago Pathfinder: Wraith of the Righteous was released for Windows and Mac. The Devs confirms that No Linux port! will be made. Anyhow, this guide will show you how to play the game anyway.
Note: You need to install steam from steam homepage and not from Software Center. Snap/Flat packages have limited Steams usage (like many other apps for that matter).
It comes in a .deb package which you only need to double click to install. Remember to uninstall Steam if you install it as a snap/flat package first.
Install Steam from Steam homepage and login.
Go to Steam Settings and activate Steam Play.
Open the terminal and copy/paste
cd Downloads wget https://github.com/GloriousEggroll/proton-ge-custom/releases/download/6.8-GE-2/Proton-6.8-GE-2.tar.gz mkdir -p ~/.steam/root/compatibilitytools.d/ tar -xf Proton-6.8-GE-2.tar.gz mv Proton-6.8-GE-2 ~/.steam/root/compatibilitytools.d/
Right click on Pathfinder: Wraith of the Righteous and select Properties
Now click Compatibility and select Proton-6.8-GE-2