[QUESTION] How do you become more advanced according to WH?

I believe that shows the rank of how the amount of units you have researched compares to others' research. By researching more the percentage will go up.

its just simply the more research youve completed, the more advanced your nation is

Oh, got it.

More specifically, y'all, the "most technologically advanced nations" ranking represents the percentage you have completed of all research levels of all units. In order to get to 100%, you actually have to complete the research for all 23 of the elite level units, too, to which most players don't even have access because they have not completed all 23 blueprint sets by chasing air drops. Without any elite level blueprints, I think you can only get to 89 or 90% in the technology rankings.