Yes, you can sign an occasional lease with a citizen of Ukraine. The Act of March 12, 2022, on Assistance to Ukrainian Citizens in Connection With the Armed Conflict on the Territory of This Country, Article 69, says that citizens of Ukraine do not have to present the premises that they will move to at the end of the contract. It is effective until further notice. Link to the law. In the case of a possible eviction, such a person is considered to possess alternate housing and can be evicted outside the rented apartment even without a guarantee of alternate housing.
Foreign citizens may not have a PESEL number. Any tenant entering into an agreement through Rendin must undergo verification. For such verification, it is necessary to have a PESEL number. Anyone who has a PESEL number and has been verified with a positive outcome can sign an occasional rental agreement with Rendin protection. If the prospective tenant you want to rent an apartment or house to does not have a PESEL number, they can obtain one. You can find more information here.
In addition, any person who signs an occasional rental agreement with Rendin protection must also indicate where they will be evicted to. Only citizens of Ukraine are excluded from this requirement in accordance with the aforementioned law.