A Gothic Kingdom in Crimea

Been thinking about the Crimean Goths and how ridiculously long they survived in some form until the 1800s. And I've been thinking, what if the Goths were more numerous and united in the Crimea? Say, they form a kingdom based around the Crimean peninsula, parts of the Southern Dnieper, and the coast of the sea of Azov from the Early Middle Ages onwards. How does such an outpost of Germanic peoples interact with the powers of its day, chiefly the Byzantines, the emergent Kievan Rus and eventually the Cumans, Mongols, Tatars and Ottomans? I'm assuming they'd at least be Eastern Orthodox Christian thanks to their proximity to the Byzantines.
Technically happened IOTL with the principality of Theodoro, it also outlasted the Byzantine Empire for a couple of decades after the fall of Constantinople. Perhaps a surviving Byzantine Empire or weakened Ottomans would not bother attacking the last of the Crimean Goths?