What about the online food ordering market. I reckon that might be an easier first step than consumer products. Here in the Netherlands JustEatTakeaway has a market share of around 90% and requires restaurants to give them a 14% provision. Restaurants don't have much of a choice, if they're not on there they miss out on a huge part of the market, it's like they don't exist. Why don't restaurants unite and develop a FOSS protocol that let's them federate, so the consumer has a central place to browse the food delivery market, but simultaneously makes the providers independant because they can run their own instance if they please. Have these types of ideas been pitched to branche organizations? Restaurants have a clear interest to develop this to free themselves from the platforms with a monopolistic venture-capital-driven strategy.

ITT: OP has an "idea" and no money. Please do all the work.

We are not your thinktank bro

Or you can just buy from other online retailers.

I think there's some misunderstanding here. Amazon is a massive logistics system. The retail storefront is a tiny part of what Amazon is today.

AWS exists because Amazon needed to solve an internal data handling problem in order to solve their logistics problems so that they could scale up. After building that system, they started selling it as a product to other businesses. The point being, Amazon's real success is based on providing business-to-business services. The retail website is the tiny public-facing bit, but it depends on the rest of the organization structure in order to operate properly.

What you're proposing is more like an eBay alternative, where the system is basically just the storefront, and the sellers listing products are responsible for their own logistics. eBay still provides dispute resolution for buyers though, and that's hard to achieve without some centralized control.

There's also the legal problems. At some point someone will use such a system as a silk road - probably sooner rather than later. Whoever is administrating and hosting it will be liable for criminal activity in the countries where the crime occurs. It will not end well.

Example 1: So you buy at toms groceries, you trust them.

[citation needed]

Could this be an app realized based on the mycelial web - amazon uses huge AI models to predict their customer's behaviour and do the logistics ... (not sure myself, but it probably won't work solely on ActivityPub)

I like the idea and it could work very well for smaller communities. In fact, theyre already doing something similar called "Werbering" (advertising ring) in germany. It takes the idea and elevates it into the digital space.