“My understanding is that Texas entered into this mutated Union as a Sovereign Republic (a free ‘country’).”
I’m only aware of 2 states that entered the union as sovereign Republics - Texas and California.
I believe VT was independent before it entered the union.
The difference is that as usual, Texas was the real deal, created in war, with it’s own Navy and consulates, a real nation. Texas had to continue fighting and defending itself during it’s period of Sovereignty.
TEXAS-*”Formed as a separate nation after gaining independence from Mexico in 1836, the republic claimed borders that included all of the present US state of Texas as well as parts of present-day Oklahoma, Kansas, Colorado, Wyoming, and New Mexico based upon the Treaties of Velasco between the newly created Texas Republic and Mexico.”
CALIFORNIA-*” Six days later, Fremont learned that American forces under Commodore John D. Sloat had taken Monterey without a fight and officially raised the American flag over California. Since the ultimate goal of the Bear Flaggers was to make California part of the U.S., they now saw little reason to preserve their “government.” Three weeks after it had been proclaimed, the California Republic quietly faded away.”*
VERMONT-*”The term Vermont Republic has been used by later historians[1] for the government of what became modern Vermont from 1777 to 1791. In July 1777, delegates from 28 towns met and declared independence from jurisdictions and land claims of British colonies in New Hampshire and New York. They also abolished slavery within their boundaries. The people of Vermont took part in the American Revolution and considered themselves Americans, even if Congress did not recognize the jurisdiction.[2] Because of vehement objections from New York, which had conflicting property claims, the Continental Congress declined to recognize Vermont, then called the New Hampshire Grants. Vermont’s overtures to join the British Province of Quebec failed.[3] In 1791, Vermont was admitted to the United States as the 14th state.”*