Please see my personal experience above. My decision whether to propose nopCommerce as a reasonable ecommerce system strongly depends on the available plugins. And (that's why I started this thread) I've naturally thought the marketplace to be the complete and only repository of available plugins - if it doesn't exist there, then it does not exist at all.
Moreover, in a particular case I can also tell you, that a customer of mine - after I had told him, that nopCommerce is the system I work with, he said to me ... "Great, website looks good and the required (payment) plugins are also listed".
That's the bottom line, at least for me.
Kind regards, Stephan