Actually, even most non religious Jews celebrate Passover. Much like Christians who only go to church on Easter. One of the best Seders I ever went to was with a gentleman who often ate BBQ Pork sandwiches when we went for BBQ...He told me he didn’t really worry about that kosher stuff, but loved the ceremony of Pesach...
They ritually wash hands multiple times a day?
https://www.chabad.org/library/article_cdo/aid/607403/jewish/Meal-Hand-Washing.htm