a. You indicate you are sola-Scriptura. But you yet insist Moses wrote Genesis in the desert of Midian without a text.
Sola Scriptura is funny that way. It does not say that "nothing happened unless it is recorded in the Bible" rather it says that doctrine has to be tested by the Bible. I think you are conflating the two just then.
My argument about the Genesis 36 chapter is
1. Genesis came before Exodus
2. Moses is the author of the first 5 books of the Bible
3. The list of Chiefs given in that chapter and then kings in that chapter are historic fact at the time Moses was in Midian..but they would also be historic fact while Moses was at Sinai... either way it is historic fact.
4. I have given several options for why Moses' text points to Israel having no king at all while these Edomite kings were reigning -- I will give another one.
I think it strikes the reader that Jacob and Esau are twins and yet Esau has a long line of kings whereas Israel had none to that point in time. His contemporary readers would have known and agreed to that argument. And they may have been supposing that just as Esau's descendants eventually organized to the point of having Kings - so also would Isaac's descendants - and possibly wonder why it is taking Israel so long as compared to Esau.
In other words the one that was "blessed" had no kings and was in slavery in Egypt. And the one that was not blessed had a long line of them and was in Canaan the entire time. That is a striking contrast for the reader.
In fact Moses told Israel that they should not have kings - just have God as King. Still Moses was shown the future of Israel - their apostasy during the time of the Kings and then God gathering them back to the land of Israel after being taken captive by Babylon.
What Moses did not do - is tell them their first king would be Saul and the second would be David or any such thing. Or that they would have kings in response to Samuel's sons. Details that would be known to a writer who is writing at the time of the Kings of Israel.
c. It is still unclear when Genesis was written even if Moses was the main contributor.
Clarity can be added by a direct message from God when it comes to a detail God has not given in scripture. That is not a violation of the "sola scriptura" method of testing doctrine. However it is generally accepted among classic Christian scholarship until the age of criticism that Moses wrote the 5 books.
And it is unclear that Exodus quotes Genesis, rather than Genesis quoting the statement of God on the mountain.
It is very clear that Exodus is about events after Genesis and is very logical to point out that Exodus is quoting Genesis. This is particularly true given the fact that all 5 books are given to Israel -- so all contemporary readers of Exodus also had Genesis. It is logical that the Author would have written Genesis first.
Knowing that does not violate the "sola scriptura" principle for testing all doctrine.
Finding out that God confirms that detail in a direct message is also not a violation of the "sola scriptura" principle for testing all doctrine.
We don't find out that God showed Abraham the days of Christ until we read about it in John 8:56 - but that is also not a denial of "sola scriptura" testing that had been going on for centuries before that John 8 statement was made.