That's not an alternate/new ethnic group, that's OTL:European Armenians
Population: 9 mln
Language: European Armenian
Descendants of Armenians who settled in Eurooe in Early Middle Ages. They are Apostolic and speak a dialect of Armenian that is close to Classical Armenian.
The Armenian diaspora has been present for over 1,700 years. … In the fourth century, Armenian communities already existed outside of Greater Armenia. Diasporic Armenian communities emerged in the Sassanid and Persian empires, and also to defend the eastern and northern borders of the Byzantine Empire. In order to populate the less populated areas of Byzantium, Armenians were relocated to those regions. Some Armenians converted to Greek Orthodoxy while retaining Armenian as their primary language, whereas others remained in the Armenian Apostolic Church despite pressure from official authorities. A growing number of Armenians migrated to Cilicia during the course of the eleventh and twelfth centuries as a result of the Seljuk Turk invasions. After the fall of the kingdom to the Mamelukes and loss of Armenian statehood in 1375, up to 150,000 went to Cyprus, the Balkans, and Italy.
Sorry to break it to you, but unless you're postulating a pre-1800 POD, the Zaporozhian Cossacks were already gone by the 19th century.Техасцы
Language: modern day Russian and Ukrainian that is and odd mix of English words
Ancestry: English, Russian and Ukrainian
Religion: Christianity, some slavic folklore
Culture: Техасцы culture is very odd with it being and odd mix of military and fun loving. As such it was odd to walk into aТехасцы home and find Cossack sabers and cattle man revolvers with most Техасцы homes could be found near rivers and grasslands which is why most Техасцы homes are stuck together forming what's called a sich. And can be found near the Sabine and red rivers and northeast Texas or Техасцы as they call it thus their name. Most Техасцы lead an agricultural like lifestyle with them mostly taking up farming, and cattle herding with them holding yearly festivals.
Population: 550,000 Mostly located along the Sabine and red rivers, and in northeast Texas
History: Техасцы which literally translate to Texans come from the Ukraine back in the mid to late 19th century when the Russian czar in an attempt to "Russianize" the land began expelling various ethnic groups such as poles, tartars and the Zaporozhian Cossacks the latter of whom began making their way Texas... the Cossacks would proceed to live up to their reputation in Europe with lighting fast raids on native american tribes and villages looting and killing and quickly retreat to their sich before the enemy could retaliate.
Though interestingly enough, one could conceive of a way to get them into North America:
Foreign help was critical to the success of the American Revolution. Many people know about the important roles played by France and Spain. But less well-known is the indirect help the US got from Russia. On this July 4, we explore how Russia accidentally helped the American fight for independence.
All this was going on around the same time as Catherine the Great moved to dissolve the Zaporozhian Sich:The Brits didn't realize they were in for a real fight with their colonists in America until the battle of Bunker Hill (or Breed’s Hill, if you want to be pedantic) on June 17, 1775. Britain had by far the biggest navy in the world, but its army, while good, was much smaller than its European rivals'. The key to crushing a revolt is to move swiftly and violently before rebels get organized. And in 1775, Britain simply didn't have the reserves of trained manpower to do this.
What Britain did have was plenty of cash. So it turned to Europe to see if it could purchase military help — and the first country that London turned to was Russia. London asked Catherine the Great of Russia for 20,000 men... There were two main reasons Britain thought Russia would agree to help: The Russians needed the money, and they hated rebels.
Russia had just concluded a successful but expensive war against Turkey, and it was also putting out the last flames of a peasant and Cossack revolt in the south, the so-called Pugachev rebellion.
So Russia had more troops than they really needed for peacetime, and a serious need for cash. The Brits hoped to have 20,000 battle hardened Russian troops in Boston by the end of 1775 or early in 1776. It's hard to imagine, but you could have seen Cossacks watering their horses in the Charles River.
In the end, the Russians decided not to help Great Britain... The Russian decision not to sell troops to Britain had a significant strategic impact. It imposed a delay on the British mobilization for war with the colonists. It was only after Catherine of Russia said no that the Brits turned to the Hessians, from Germany, to provide them with the manpower they needed. But the delay might have been critical.
As a result of the Russian diplomacy, Britain was forced to delay its counter-offensive against American patriots until August 1776.
Had a division of Russian or Hessian troops arrived in Boston in late 1775 and driven away Washington's infant continental army, that could have swayed a lot of minds in America as to the wisdom of even declaring independence. Instead, the rebels were able to get much more organized, dig defenses, obtain resources like gunpowder and cannon and provide their troops with training and equipment.
So, potential POD: Catherine the Great agrees to help the British during the American Revolutionary War. Hoping to kill two birds with one stone, the Empress gives the Zaporozhian Cossacks a choice: either become part of the Russian Imperial Army or go to fight the revolutionaries in North America where you can earn fortune and land for helping the British. Rather than being sent into monasteries or Siberian exile, Otaman Kalnyshevsky and his loyalists are sent overseas to Boston...In May 1775, Russian General Peter Tekeli received orders to occupy and destroy the Zaporozhian Sich from Grigory Potemkin, who had been formally admitted into Cossackdom a few years earlier. Potemkin was given direct orders from Catherine the Great. On 5 June 1775, Tekeli surrounded the Sich with artillery and infantry. He postponed the assault and even allowed visits while the head of the Host, Petro Kalnyshevsky, was deciding how to react to the Russian ultimatum. The Zaporozhians decided to surrender. The Sich was officially disbanded by the 3 August 1775 manifesto of Catherine, "On the Liquidation of Zaporizhian Sich and Annexation thereof to Novorossiya Governorate", and the Sich was razed to the ground.
Some of the Cossack officer class, the starshyna, became hereditary Russian nobility and obtained huge lands in spite of their previous attempts to relocate the Sich to either North America or Australia...
The leader of the Zaporozhian Host, Petro Kalnyshevsky, was arrested and exiled to the Solovetsky Islands (where he lived to the age of 112 in the Solovetsky Monastery). Four high level starshynas were repressed and exiled, later dying in Siberian monasteries. Lower level starshynas who remained and went over to the Russian side were given army ranks and all the privileges that accompanied them, and allowed to join Hussar and Dragoon regiments. Most of the ordinary Cossacks were made peasants and even serfs.
In 1780, after disbanding the Zaporozhian Cossack Host, General Grigorii Potemkin attempted to gather and reorganize the Cossacks on a voluntary basis, and they helped to defend Ukraine from the Turks during the Russo-Turkish War (1787–1792). He was able to gather almost 12,000 Cossacks and called them the Black Sea Cossacks. After the conflict was over, rather than allowing the Cossacks to settle across Southern Ukraine, the Russian government began to resettle them on the Kuban River. In 1860, they changed their name to the Kuban Cossacks.
From there, you can postulate the Zaporozhian Cossacks becoming part of the North American ethnic landscape much like the Hessians did OTL. Heck, you could even postulate a scenario where Otaman Kalnyshevsky & his troops switch sides with Petro as a result becoming known as one of the "Founding Fathers" and getting his face carved into an ATL Mount Rushmore