"Bigger" as in higher market cap. How big are Amazon and eBay these days in terms of dollar value sold via their market places? If eBay is anywhere near Amazo

"Bigger" as in higher market cap. How big are Amazon and eBay these days in terms of dollar value sold via their market places? If eBay is anywhere near Amazon and Shopify stores outsell eBay, that would be pretty spectacularely. Shopify stores live on their own domains, right? No reviews, no central discoverability, no nothing, correct?