The Driver Manager application should handle this for you pretty easily. Just select the latest/recommended NVIDIA driver version.

Note: In my experience (as of January 2025) the partially open-source nvidia-driver-*-open drivers don't always work completely (e.g. things like sleep will be buggy). Thus I'd avoid them and install the proprietary versions instead.

Enable the non-free and non-free-firmware sections in your base Debian repos in /etc/apt/sources.list:

deb http://deb.debian.org/debian/ trixie main non-free-firmware non-free
deb-src http://deb.debian.org/debian/ trixie main non-free-firmware non-free

deb http://security.debian.org/debian-security trixie-security main non-free-firmware non-free
deb-src http://security.debian.org/debian-security trixie-security main non-free-firmware non-free

# trixie-updates, to get updates before a point release is made;
# see https://www.debian.org/doc/manuals/debian-reference/ch02.en.html#_updates_and_backports
deb http://deb.debian.org/debian/ trixie-updates main non-free-firmware non-free
deb-src http://deb.debian.org/debian/ trixie-updates main non-free-firmware non-free

Update your apt sources, then install the Linux kernel headers for your architecture:

sudo apt update
sudo apt install -y firmware-misc-nonfree linux-headers-amd64 # change this based on your architecture

Install the NVIDIA driver w/ DKMS:

sudo apt install -y nvidia-kernel-dkms nvidia-driver