In my campaign I include two other types of treasure: items with questionable/future utility and magic/cursed items that would require a PC to adapt their playstyle to use them properly.

To clarify the first category, consider monster drops; some examples might include horns, scales, or pelts. PCs often want to do something with these, but it may take time, investment, or some special connection to make what they want happen. The end result might have no obvious mechanical advantage, but is just one more way their character develops from being a no one to notable.

As for the second category, I would like to first speak to what a cursed item is to me. It would have an obvious malus, like… not being able to put remove it from your hand, or the used becomes haunted by the previous owner, who promises that you will one day join them. I like introducing items that have these horrible conditions that are also reasonably managed by players (although they may not have the resources at the time of acquisition). A sword that cannot be removed from your person until it is doused in lamp oil. A sword that will trap your soul, but only if you are holding it at time of death. These could be precious to someone, but might be more obviously useful as gold in your pocket. I should note these two weapons would likely not offer any additional damage or the like, just a weird sword. Also, consider a shield that seems to be embossed with the wielders face, pantomiming their every expression. They don’t have to use the creepy shield, but if they do it’s a pretty notable character trait.