If anyone else is still experiencing a similar issue, I was able to solve by doing the following:
There were actually two problems, the first was that Rocky was attempting to use my CPU integrated graphics instead of my GPU - deactivating it in the BIOS prior to installing Rocky fixed a ton of issues with the Rocky installer and pre-nvidia driver GUI environment.
Secondly, it seems that the nvidia post-install scriptlets actually terminate the nouveau drivers immediately, which was why my GUI would break mid-driver install. Installing the drivers in a terminal-only environment did the trick:
Reboot into the terminal without loading the GUI by changing the systemctl default mode:
sudo systemctl set-default multi-user.target
sudo systemctl reboot
Then follow the nvidia driver install steps when you boot into the terminal. Install the “open-dkms” version of the driver.
After the drivers install, switch the systemctl default back to the GUI and reboot:
sudo systemctl set-default graphical.target
sudo systemctl reboot