My question was put on hold as primarily opinion-based and one of the mods even called it a 'random speculation' even though I provide facts in the question to support my theory.
I don't watch GoT, so I am not sure about the question. However, if you take a look at it, you will find so many assumptions without source(s) backing it up. And in the end, you asked what do you think. I am sure we don't ask for opinions of the people here. It's not an internet poll.
Here are the lines where I see the problem (with the emphasis on the problem parts).
So, I assume, it was the magic of dragons that laid the way for the dead over the magic of the Wall. But the main reason for dragons to be beyond the wall in that particular spot was Sandor's vision in the flames in S7E01 "Dragonstone".
I think it is reasonable to assume that the Night King needed dragon magic to get through the Wall and its magic.
It seems to me that if the Lord of Light is really the Night King then it's all about the struggle between the Night King and the Three-Eyed Raven.
And the last one,
- What do you think? Are the Night King and the Lord of Light the same thing?
The last sentence makes the question look like that you are seeking the answers based on opinions rather than facts and the expertise.