There’s a lot of controversy over Yom haShoah as a date. One of the key issues is this: traditionally, the ways Jews mourn communal tragedies is through establishing a fast day. It’s forbidden to fast during the month of Nisan. It’s hard to pick any specific date to commemorate a tragedy as enormous as the Shoah, but one which seems appropriate to me would be 16 Marḥeshvan, the anniversary of Kristallnacht, the November Pogrom. This piyyut is a seliḥah for Kristallnacht, to be recited on 16 Marḥeshvan (or 15 Marḥeshvan on years like 5782 where the sixteenth falls on a Thursday).