Customers of shipping companies are price driven. They don’t give a fig about sustainability.
Vessel owners are cost driven. They don’t give a fig about sustainability.
Banks are profit driven. They don’t care about sustainability. They just want customers that can repay their loans.
So who ( other than crazy government corporate welfare programs) is actually going to pay the high extra costs of building and operating “sustainable “ ships?
Where is all the extra money to pay for sustainability going to come from?