I’ve found that the rise of Apply Pay as a payment mechanism on random sites has been helpful in getting me off of Amazon. Often it’s just as easy to order something direct if they have Apple Pay (or ShopPay, but I have other issues with them) and the same price as Amazon. Plus discoverability is awful on Amazon anyways. Still don’t get the Whole Foods return ability when not shopping from Amazon, but not punching in…
To me, the key feature of Amazon is the fast delivery with Prime. Do other merchants offer fast delivery often enough? Regarding credit cards, I started using privacy dot com for virtual, merchant-locked cards. It protects against (rare) card details leaks, but, of course, does not give you any points or cashback.
What's ironic is we still make purchases on Amazon that don't require their fast shipping. We're just conditioned to expect it. I'm thinking TVs, books, project supplies, art, etc.