Your low-end nvidia gpu likely doesn’t support listing processes using nvidia-smi.
In offload mode, you can run applications on the nvidia gpu like given in the link:
__NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia glxinfo | grep vendor
If you want to set the nvidia gpu as primary, create
/etc/X11/xorg.conf.d/10-nvidia-primary.conf
Section "OutputClass"
Identifier "nvidia"
MatchDriver "nvidia-drm"
Driver "nvidia"
Option "PrimaryGpu" "yes"
EndSection
and set your DM/WM to run
xrandr --setprovideroutputsource modesetting NVIDIA-0 && xrandr --auto
on startup.