The key is 100% boycotting all services provided by a company. Wikipedia’s list of Amazon product/services as reference (https://en.wikipedia.org/wiki/List_of_Amazon_products_and_services).
Incidentally, I know entire neighborhoods that don’t have other grocery stores besides Target/Whole Foods, not to mention that AWS is the cloud computing industry standard… As a personal example, my vet-prescribed cat foods are manufactured by Purina, a subsidary of Nestlé (needless to say, a separate but also extremely evil large corporation)
I’ve spent years now trying not to consume products from companies I consider immoral. There are a lot of them and, realistically, you won’t make a big dent or bring the company down. The average person is, by definition, average, so a boycott based on people doing the good thing at the expense of some personal discomfort will always fail.
But that doesn’t mean it’s pointless. Companies like Amazon are almost impossible to compete with because of their size. The most important impact you can have as a consumer is not that the lack of your personal revenue is going to keep the likes of Jeff Bezos up at night. It’s that you’re providing revenue and a user base to alternative businesses that are struggling to exist in a world where most people just use Amazon.
You can make a real difference this way! Focus on growing competitors rather than hoping the bad company will go away because of your abstention. Kind of like using Lemmy instead of Reddit.