Disable the iGPU from BIOS and enable early KMS for the nvidia GPU by adding in the /etc/mkinitcpio.conf at the MODULES line:
MODULES=(nvidia nvidia_modeset nvidia_uvm nvidia_drm)
then run:
sudo mkinitcpio -P
sudo update-grub
Not sure, but maybe also remove plymouth from HOOKS, the package and also switch from gdm-plymouth to gdm