I want to manufacture graphics cards/GPUs is Nanoelectronics the best thing to study?

And which major focuses more on nanoelectronics, electrical engineering or computer engineering?

Definitely computer engineering.

Search for Nvidia and AMD jobs. Keep in mind that these GPU’s are more than just graphic cards, they are used in AI, deep learning, self-driving cars, etc. That’s why if you search for Nvidia, you’ll see them hiring AI research/development engineers and Deep Learning Engineers.

They will be looking for Computer Science, Computer Engineering, Electrical Engineering or some type of interdisciplinary major. They even need Physics, mathematics and other related fields.

Good Luck!

Graphics cards and gpus on the manufacturing require understanding of the following:
Integrated circuits and VLSI which would be electrical or computer engineering.

And semiconductor device design/physics which is mostly electrical engineering.

And of course CS is needed for all the software. I’ve never heard of too many nanoelectronics majors they are mostly just specific classes you take.