Margins in the shipping industry are typically rather low and it's offset by scaling well with container ships of proportions only limited by the canals they must traverse. This ship is positively microscopic in comparison. I would imagine it's only cost effective for very specific types of cargo.
There are hybrid options with flettner rotors and deployable kite sails for partial fuel savings on specific routes, but it's all rather experimental.
> I would imagine it's only cost effective for very specific types of cargo
I imagine you're close to correct, but that some people might be willing to pay a premium for types of cargo that normally would not turn a profit. "Fine goods", as my local Specs puts it.
the French could keep shipping mass produced crappy cars economically on big ships, and then small numbers of cars de luxe on these bougie ships, and advertise the... "car bon offsets".
There are hybrid options with flettner rotors and deployable kite sails for partial fuel savings on specific routes, but it's all rather experimental.