In the current documentation, under "GPU Rendering" the following appears:
"For laptops which also include an integrated graphics card, use the NVIDIA Control Panel to set the preferred graphics card to the discrete card." This is true only for Windows 10.
In Windows 11, this setting is not controlled by the NVidia app, but by the Windows 11 Settings app. Go to "Settings > System > Display > Graphics." Under "Custom options for apps," add Stager (or any other desktop app) by choosing the Browse button and navigating to the .exe file in Program Files\Adobe\Adobe Substance Stager. Choose "High Performance" in the options dialog.
Additionally, the NVIDIA Control Panel must be reset in order to work correctly in Windows 11. It will crash within a few seconds of launch, so is unusable until reset. When this is done, it correctly shows that choice of GPU is now handled by Windows, not by the NVIDIA Control Panel.