It can be used during one Ambition, it can be used in the more expensive option to upgrade one of the lodgings and it can be used in an inprofitable manner for a repeatable grind during the late-game.
originally it was used for “having a complete set of scraps items” which was historically somewhat difficult to grind for but i suspect EPA creep and an increased diversity of acquisition methods for most of them has made that particular accomplishment pretty much irrelevant
You stand correct and it’s the same for the Fire dream extension too.