Yes, I see where you're going.
The title says upgrade from buster to bullseye, the other thread was same, upgrade. But this one appears to be more of a fresh install, in which case, same issue will come up right? Might need to try disabling the nvidia in computer settings and try with on-chip video if that option is available in settings.

Fun facts:

The Debian installer apparently has 5 virtual terminals, they are:
1: VT1 = Text mode
2: VT2 = Second terminal, or console
3: VT3 = Third terminal, or console
4: VT4 = Installation logs and other data
5: VT5 = Graphical Mode

Key bindings for switching to any other, if you are installing in text mode which has no mouse support. Left Alt + Fx key. So if you want to run a command and switch to VT2, you would hit Left Alt + F2, when you're done, to go back to the installer hit Left Alt + F1.

If you are in graphical mode where you have mouse support, Left Ctr + Alt + Fx, to run a command you can go to either VT2 or VT3, Left Ctrl + Alt + F2/F3, to go back to the installer, Left Ctrl + Alt + F5.

In a case like this, you would want to use either Graphical Expert or Expert (text) mode. You will be asked low and high priority questions, one of which I noticed last week that I did not notice in the past, which is "Do you want to add non-free sources", to which I said yes. Because this is where proprietary Nvidia drivers come from.

During installation at the tasksel stage you select the tasks, I don't actually recall if there is an option here to add specific packages, I don't think so. Next it will install all the extra software, then you're taken back to the menu where you select the next step which should be boot loader related. Here you may choose to switch to VT2 or VT3, and install your Nvidia drivers, or after boot loader steps where it says "Installation finished, remove install media and press enter to reboot ".

This is providing you have selected to enable non-free and have an internet connection. So by rights, when you reboot, you have working graphics with proprietary drivers. The version of Nvidia driver I have installed is 430.64-4, according to documentation found on my system at /usr/share/doc/nvidia-driver/README.txt.gz, the Geforce GT 730 is supported. So theoretically, it should be as easy as switching to VT2 or VT3 and issue command: apt install nvidia-driver, after it's done, switch back to the installer.

Another option, in rescue mode, you can select the root partition, enter a terminal which should put you in a chroot, I believe you should also have internet access in this chroot if you have a wired connection, which allows apt to download required packages to install nvidia-driver.

My "two cents" on the issue.

I was "distro-hopping" for about ten years, and in 2005 I stuck with Debian. Not exclusively, though, I had other computers with different distributions, but my MAIN computer is Debian.

From what I have experienced, yes, Debian Stable is rock solid, BUT when it comes to other distributions Debian Testing is equivalent to other distributions "Stable". {bad-word}, some other distributions "Stable" instance is equivalent to Debian Unstable (Sid).

So, as others have said, if you want ROCK STEADY, use Debian Stable. If you want the equivalent of other distributions concept of stable, use Debian Testing.

Now, as I have said above, this is merely my opinion. I could be... well wrong or merely misguided.

{{{Also, if you don't have access to DSL, then just stick with Stable..... just saying.....}}}