I'm sorry. I just relied to the information on the Fonic website. But in Leipzig there's a shopping mall in the central station ("Promenaden Leipzig Hauptbahnhof" at Willy-Brandt-Platz) which is opened on Sundays and on public holidays
from 13:00 through 18:00 and where there is REWE (supermarket), Rossmann (drugstore) and Saturn (electronics). According to
Rossmann Filialsuche the Rossmann store is opened Sundays from 9:30 through 20:00 and REWE should be
opened from 12:00 through 18:00. I expect them to be opened on Easter Monday at the same time, too.