I’ve spent many xmas’s in Seville over the years. The most recent being 2024. The decorations along Av. de la Constitución and Plaza de San Francisco are stunning. We love the atmosphere in Seville at this time of year.
We eat early on xmas eve at the same restaurant, as we know it will be open. The streets are generally quiet in the afternoon and many shops/markets close early.
From our experience the streets are quiet xmas morning, but many restaurants/bakeries open later in the day. We tend to dine when the restaurants open, otherwise they are packed. We cook dinner in our apartment xmas night, I’m not sure what's open xmas night.
Boxing day in chaotic in the evening with massive crowds lining the streets enjoying fiestas.
Depending on your location, supermarkets are dotted everywhere.