products.csv or products.xlsx plus an images folder. In the sheet, use images like front.jpg|back.jpg, variant_images like Color=Red>red.jpg, and combination_images like Size=Large+Color=Red>large-red.jpg.product_id, name, price, stock_quantity, description, images, variants, variant_images, combination_images. Advanced JSON columns are still supported for exact variant data.image_urls still work.