Simplified Installation with Nvidia's Script
Visit the download page in Desktop Mode (Steam button => Power => Switch to Desktop) on your Steam Deck.
Download the installation script provided by Nvidia.
Once downloaded, extract the zip file and click on the "GeForceNOW_Setup" script.
Select "Run" to launch the script.
Follow the on-screen instructions to complete the automatic installation of Google Chrome and the configuration of the browser for use with Steam Deck controllers.
Once the installation is complete, click "Return to Gaming Mode" from the desktop and navigate to "Non-Steam Games" in the Steam library to launch GeForce NOW.
Tips and Tricks
Make sure to adjust the controller settings to enable the use of the trackpad as a mouse within the streaming service.
Use the GeForce NOW streaming overlay by long-pressing the Start button on Steam Deck for smoother navigation.
For some games, such as Genshin Impact, you may need to enable gamepad input in the game settings.