MK Consult
To work legally in Poland, Ukrainian citizens need a PESEL or a residence card. Under a special law (Dz.U. 2022 poz. 583), it is possible to use PESEL UKR, which is issued to Ukrainians staying in Poland. Therefore, you need exactly PESEL UKR if you are a Ukrainian citizen【4:1†source】.
What is your plan for working in Poland?