A second foreign passport is issued to persons who have reached the age of 18, who regularly travel abroad on business trips and for which it is necessary to issue visas in advance. This need is justified in the application, which is submitted together with other documents. Issuance of a second passport of a citizen of Ukraine for travel abroad is possible only in the presence of a valid foreign passport. A citizen of Ukraine cannot have more than two valid foreign passports.
Go to any accredited key certification center and provide the completed registration form, your passport details and your taxpayer identification card registration number. The complete list of such centers is at the link.
You can read more about the conditions for obtaining German citizenship here: https://handbookgermany.de/uk/citizenship.