How does Gehinnom work?

Greetings

I am Christian and I believe in purification after death.

I think of ourselves as 100% clean after birth but as we age we get spiritually tarnished by the sins we commit, and after that to reunification with God we must become 100% clean again.

I think Jews call this Gehinnom and depending on the 613 mitzvah you don’t commit you stay in Gehinnom longer (correct me if I am wrong)

So is gehinnom equal to hell in Christianity or purgatory? Do you know any other Christian sect that does something similar to gehinnom except Catholicism?

How purgatory works is after death, saved Christians go to purification before heaven. Prayers are offered to the dead to pass this stage swiftly.