If one reads Church Slavonic, one can easily verify that the Kyivan liturgical books in the seventeenth century were not identical either with the pre-Nikonian Moscow editions or with the Greek editions, but were much closer to the pre-Nikonian Moscow editions than to the Nikonian editions - all one needs to do is put, say, both texts of the Divine Liturgy of Saint John Chrysostom on the table and compare them.
Once the persecution broke out in Muscovy, significant numbers of Old-Ritualists (who continue to use the pre-Nikonian editions) began to take refuge in other countries, including Ukraine. Political developments in Eastern Europe placed Galicia and Bukovyna within the territory of the Austrian Empire, and the Old-Ritualists, who already had some people in Bukovyna, established at least two monasteries in and around the village of Bila Krynytsia (or Alba Fontana or Bielaia Krinitsa, depending on which language one cares to use). When Tsar Nicholas I renewed and intensified the persecution of the Old-Ritualists in Tsarist Russia, the Old-Ritualists decided that the best thing to do was to establish a bishopric at Bila Krynytsia. They obtained the consent of the Austrian Emperor for this project, and Metropolitan (now Saint) Ambrose, retired Metropolitan of Bosnia, joined them, becoming the first Metropolitan of Bielaia Krinitsa. After World War I, that part of Bukovyna was ceded to Romania, and continued to be the seat of Saint Ambrose's successors. Parishes and even dioceses developed inside Tsarist Ukraine, but once the Soviets came to power people (including Old Ritualists) began fleeing from persecution, and some more parishes were organized in Western Ukraine (which at the time was governed by inter-war Poland).
During and after World War II it was safer for the Metropolitan of Bielaia Krinitsa to live in Romania; Bukovyna became part of the USSR. Saint Ambrose's present-day successor, Metropolitan Leonty of Bielaia Krinitsa and All the Old-Orthodox Christians, continues to live in Romania, at Braila. There is still an Old-Ritualist diocese in Ukraine, with an Archbishop at Kyiv, and a growing number of parishes function in Ukraine.
By the mercy of God, the most important Church at Bila Krynytsia - the splendid Catholicon of the Dormition, built in the early years of the twentieth century - was not too badly damaged either in the world wars or during the Soviet period, although the monasteries were closed. The Catholicon of the Dormition was restored for the canonization of Saint Ambrose in the nineteen-nineties and is still in use for divine services, particularly on great occasions.
In the inter-war period there was a lovely chapel set aside for the Old-Ritualists in L'viv, but my efforts to locate the antique icons from that chapel have met with no success. What with all the demographic changes in L'viv since the beginning of World War II, I would not even hazard a guess as to whether there are enough Old-Ritualists in and around L'viv to maintain a parish, but if there are I would expect them to be in the process of organizing for that purpose.
Fr. Serge