What kernel versions do you have there?
You still should be able to boot with nomodeset and the oldest kernel version that you have in GRUB boot menu options.
If newest kernel-latest is not working for you then you can try the older kernel version e.g.:
sudo qubes-dom0-update kernel-latest-6.8.6
If this won’t work as well then you can remove the kernel-latest versions in dom0:
sudo dnf remove kernel-latest kernel-latest-6.8.6 kernel-latest-6.10.3
Then I guess you can try to use proprietary NVIDIA driver instead of nouveau:
Or you can just use nomodeset and add the nomodeset option to the GRUB menu boot options persistently so you won’t need to add it manually every time:
In dom0 terminal edit /etc/default/grub file:
sudo nano /etc/default/grub
And add this line at the end of the file:
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX nomodeset"
Then rebuild the GRUB config in dom0 terminal:
sudo grub2-mkconfig -o /boot/grub2/grub.cfg