I’m updated to ZorinOS 15.3 and I am using the nvidia-driver-450.
However,
In the prime profiles available, I only have NVIDIA and Intel and it doesn’t have NVIDIA on-demand.
Any ideas what to look for or try to have such option?
Hi brunoais, and welcome to the forum!
Don’t know if this article might help?:
I don’t have a high end nVidia graphics card and only ever use the Nouveau (non-proprietary) drivers. 
Wow… I didn’t get a warning someone had responded me!
Unfortunately, it doesn’t work because those instructions still force me to logout and log back in to change the GPU in use for processing. Any alternatives?