Hi @Melhopenot
Firstly, it is only possible with certain refugee status to go directly into citizenship. It is possible if their permit is according to paragraph 25,1 or 25,2 of the Aufenthaltsgesetz. If they have a permit according to the paragraphs 25,3 / 25,4 / 25,5 they first have to get a different type of permit or qualify for permanent residency (Niederlassungserlaubnis) before they can then be eligible for citizenship.
The German government is currently passing a new law regarding citizenship. It is planned to come into effect in the first half of 2024. Under the current law, there are exceptions to the requirement to be financially secure. Such exceptions are possible if the person is not responsible for being without work, e.g. as single parents, pensioners, people with a serious illness or who have tried but cannot find work.
The new law as planned will remove many of these exceptions and so it will be no longer possible for many such cases to become German citizens without work.
I am not aware of any possibility to secure citizenship via a guarantee from a third-party. Such a guarantee (Verpflichtungserklärung) is possible in cases of specific residence permits, e.g. to get married or coming to study in Germany. Citizenship is not one of them as it is an unlimited status.
Best,
Éanna