Why on earth would you want to install Pamac for this? Completely unnecessary (and it wouldn’t work).
@mmtech use the option -u with arch-chroot to specify a non-root user:
arch-chroot -u your_user_name
That will let you build a package using makepkg:
git clone https://aur.archlinux.org/nvidia-470xx-utils.git
cd nvidia-470xx-utils
makepkg
Then chroot, and cd into the build directory, and use pacman -U to install the package(s):
pacman -U nvidia-470xx-dkms-470.141.03-1-x86_64.pkg.tar.zst nvidia-470xx-utils-470.141.03-1-x86_64.pkg.tar.zst