A new kind of ship that is large, with an interior like a house, I guess this should be doable even before the OCO is completed.
The idea is that so far nomad living is not really that doable, since everything in the game requires a lot of space. A lot of people in the real world live a nomadic life on boats, and not all for limited periods. With a literal house on water that can move (and be actually locked, unlike ship cargos) people would have the chance to be nomads for real, this would also help greatly explorers that so far cannot bring with them anything that doesn't fit inside the cargo, cannot count on the safety of the cargo nor they can leave anything outside like a bed for sleeping because it wouldn't be safe. It would also be appreciated by merchants probably.
It would also be a great match with stilt houses on water and other shallow water dwelling ideas, but I know we're not getting that before OCO is completed since they already made the example of bridges needing it.