There have been, and continue to be many companies focused on harnessing wind power for reducing cargo ship emissions. OutSail's (proposed) innovation is putting the sail into a standard inter-modal container form-factor.

but like what other form factors exist for container ships? nobody thought to put the sails into containers on a container ship before these guys?

I'm not sure what other options have been considered (by would-be market entrants), but OutSail appears to be the first company that is attempting to package a sail into a 'box'. Some other companies have made devices like kites which were relatively vessel-type agnostic.

I think one of our main innovations is how to make a very tall and rigid sail without a rigid mast. But you're right, once we figured out how we can roll up a 60m sail into a small package it was obvious to put it in a cargo container.

Had no clue, excited to explore OutSail’s approach! Thanks for mentioning them