Can German soldiers who went to fight in Ukraine have access to banks?

Yes.

People from anywhere can visit local banks. It mainly depends on whether the bank accepts them. Naturally, German soldiers can also visit banks in Ukraine.

Ukraine is located in eastern Europe, on the northern coast of the Black Sea and the Sea of ??Azov. It borders Belarus to the north, Russia to the northeast, Poland, Slovakia, and Hungary to the west, and Romania and Moldova to the south.