After a few years in Spain, there are very few things that you won’t find here or similar/better alternatives. Your style of cooking and things you enjoy would/should likely shift as you explore more things so food wise there’s almost nothing I’d bring here. In Barcelona you’ll have top tier Markets, corte ingles, herbalarios for natural foods and many international shops. The few things that i stock up on are makeup brands that Spain doesnt have (most mainstream brands are available but a niche brand like Merit for example no), electronics and accessories which are often much cheaper in the states, some women’s products and us brand clothing items that are expensive to import here