Thet are very common in Lithuania, to the point where I’d say around 20% of new phones being sold are from Xiaomi. They expanded heavily into other industries, like home automation, with prices that are a fraction of what other manufacturers would ask for their hardware.
My prediction is that their market share is going to substantially grow. Xiaomi phones are much cheaper in terms of the hardware they offer. A Xiaomi Poco F3 costs €350. A comparable device from others is probably in the €>450 range. An iPhone's probably in the €>800 range.