Camellia Sinensis is the species used commercially for tea leaf production.
India, China, Indonesia, are among places it is farmed for tea…S.E. Asia is the main area it’s produced.
It is grown in Crimea on the Black Sea…the “Sochi” cultivar might be the hardiest. Only commercial production of any size in the United States is near Charleston, SC.
Anyone growing citrus can grow tea…(here that means inside or a greenhouse)… it isn’t quite as hardy as c. sasanqua.
I have a few c. sasanqua I’ve planted for a paying customer over the years…most live if planted on N or NE side of a home in z6 and z7. In places like Charlotte NC or Columbia SC they’re a ‘no brainer’.
If you succeed growing c. Japonica, then you likely can grow c. sinensis.
I’ve not produced enough to answer your question on processing the leaves…either as green tea or dried…but if you’ve done homemade herbal teas, you can do c.sinensis tea.