I have not done one personally, but a very close friend of mine did something like this in his younger years. Post college, he needed a life reset and so quit his job. Jumped on a frieghter and just went. He made arrangements to be dropped off on one of their island stops (Vanuwatu or Fatuhiva or something like that. He told me about this over a decade ago; hence, parts may be slightly inaccurate, or worse, misspelled.) They just dropped him off. He spent several months living with the natives. And then they picked him up and he enjoyed the remainder of his trip. Lots of little stops here and there before getting home.
A chance to see and experience a dozen+ cultures. A lot of quiet time for self reflection. His journey had about a half dozen to dozen other travelers on it (very small group). Everyone got to know everyone else pretty well in that time, given the small cramped quarters.
It was a big reset in his life. One that he loves and is extremely fond of.
Your link looks incredible. I've done a crossing on the QE2 before it was replaced with the QM2 and it was a wonderful trip & experience. I can only image that this would be like that but better and longer.
Sometimes the ability to disconnect and back away from it all offers the greatest perspective. But remember. No matter where you go, there you are.
I hope this journey offers you what you are looking for.
Kindest Regards,
-Chris