You can read more about the conditions for obtaining German citizenship here: https://handbookgermany.de/uk/citizenship.
Romanian citizenship for Ukrainians can be obtained in several ways:
On the basis of birth. If one or both of the child's parents are Romanian citizens, the child automatically acquires Romanian citizenship at birth.
On the basis of adoption. A child who was adopted by a Romanian citizen receives Romanian citizenship.
On the basis of naturalization. A naturalized citizen of Romania can become a person who has lived in Romania for at least 5 years, has a legal income and knowledge of the Romanian language at a level sufficient for communication.
On the basis of repatriation. A person who has ancestors who lived on the territory of Romania can obtain Romanian citizenship on the basis of repatriation.
Obtaining American citizenship by immigrants occurs through the naturalization process, the main conditions of which are:
reaching the age of 18;
5 years of stay in the USA as a permanent resident (3 years, if the resident status was acquired by marriage to a US citizen);
residence for at least three months in the territory of a certain state before the date of submission of the application to the local immigration office;
command of the English language;
knowledge of the history of the USA and the foundations of the state system and legislation;
decent lifestyle (absence of criminal record, unpaid debts, etc.);
Pledge of Allegiance to the USA and Pledge of Allegiance to the US Flag.
Unlike permanent residents, US citizens have no voting rights, can stay outside the country without losing their legal status, and are not subject to deportation.