The "Yankee" government was the government of the United States of America. Not even Jefferson Davis disputed that claim.
NEVER recognized the Confederacy as a separate nation.
NO COUNTRY ON EARTH recognized the "Confederacy" as a separate nation.
WV was created out of VA’s sovereign territory; which violated the Constitution.
This is your opinion, but it is not the opinion of the people of West Virginia, or the Supreme Court of the United States. Article IV Section 3 makes clear that new states may be formed from existing States by acts of their legislature. The legislature of Virginia declared itself void by its act of secession. The Wheeling Convention was therefore legitimate to represent the people of Virginia. It did so, and announced the formation of a new State in compliance with Article IV Section 3. The Supreme Court upheld this decision, and the admisssion of West Virginia was ratified by Congress.
The theory that the Constitution was a compact among States which retained their rights to remove themselves from it was settled when the various armies in rebellion surrendered. You can refight that war if you wish, but that won't change the historical outcome, nor invalidate decisions of the Supreme Court, nor acts of Congress.
Just because everybody says something is right, doesn’t make it right. The Supreme Court has been wrong n so many cases that it is laughable to cite them as supreme anything (see Dred Scott, Roe v. Wade, Wickard v. Filburn, Kelo v. City of New London, etc.)