There are 2 steps to follow for this.

1. Install RPM Fusion in Fedora Silverblue.
2. Install NVIDIA drivers and Steam from RPM Fusion. (The Flatpak Steam is not able to access the discrete graphics card.).
3. Install “Nvidia System Monitor” from Flathub.

Install RPM Fusion

sudo rpm-ostree install https://mirrors.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm https://mirrors.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm

I just copied this from https://rpmfusion.org/Configuration#Command_Line_Setup_using_rpm.

Once the above command is run, reboot.

Install NVIDIA Drivers and Steam

rpm-ostree install akmod-nvidia xorg-x11-drv-nvidia xorg-x11-drv-nvidia-cuda steam

I tried using Steam from the Flathub, but it could not see the NVIDIA graphics card.

Install “Nvidia System Monitor” from Flathub

This will allow you to make sure that your NVIDIA graphics is actually being used. You don’t really need this, as the extreme heat and fan noise will tell you. But this give a bit more additional details.