I used to like Newegg. It's Chinese now.
Not to rain on your parade, but how does that one help? Germany is just as terrible a globohomo communist dictatorship as USA.new and used books - bookfinder.com - often the best deal is on eBay or a non-Amazon site.
groceries - Lidl, Aldi (German)
Hardware, tools - Harbor Freight (Chinese)
Miscellaneous stuff - kitchen supplies, greeting cards, cleaning supplies - Dollar Store (Chinese).
Furniture - Facebook marketplace, Craigslist.
Well I'm from Croatia, where we still have small and medium local supermarket chains whose owners I am able to see in person walking throughout my neighborhood like any other citizen, so I might be spoiled for choice. For example, here I make a point of avoiding the globohomo monsters of Lidl and Kaufland and shop at the local ones instead, making a point to buy Croatian products whenever possible.Well it doesn't concentrate with Bezos and leaves more money in your pocket.
But please tell us the perfect place that is cheaper and doesn't fund the beast. We are waiting.