For selling single items on an occassional basis, Anibis.ch or Leboncoin.fr work well. But if what you want is an online outlet to market your line of products, they do not compare to Amazon. Amazon's reach is much wider, customers rely on Amazon standing by what they purchase and you use their shipping network. Your customers also get free shipping provided by Amazon if they have Amazon prime.
Anibis and Leboncoin, on the other hand, are only online outlets for ads placed by individuals. They will place your ads, for a fee, and of course you do not have to set up a bank account or provide them your bank account information. Amazon, on the other hand, will sell your products: they will list them in their website, sell them, ship them and receive payment for them. They then have to pay you for all the items they have sold for you. Hence, the need for you to provide them with a bank account to which they can transfer all payments received.
For information on how to become an Amazon retailer, go here:
or here, for information in english, regarding selling through Amazon UK:
There are only 5 countries in Europe where Amazon operates, other than the UK and they are in the Eurozone (France, Spain, Germany, Italy and the Netherlands). They do not operate in Switzerland. Hence, if you are based in Geneva or Lausanne, they will want you to have or set up an account in Euros in a French bank, though you probably can set it up in Germany, if you wish.
It is all a matter of where you will be shipping your items from and what particular Amazon country you want to be primarily associated with, though I think you can advertise you product on more than one European country: if you work with the French site, I think they can sell your products through the other European Amazon websites as well.