So, there's a decent amount of variation in psi headbands, but headbands are pretty much the only psi equipment. You can modify certain armours with a psi beetle carapace to give a psi bonus but that's pretty much it for the base game.
Expedition adds a lot of psi stuff compared to the base game. Things for the weapon slot that are actually worth using as a pure psi build, for example. The psi crab carapace that can be used to make heavier psi armour.
I would really have liked the option for custom made psi staffs or spears.
However there's still far less choice for psi equipment than there is for weapons and normal armour. Especially when it comes to unique weapons or armours.
A unique psi headband for example could be a Thought Control headband that lets you restore a portion of psi points equal to 10% of the damage done by Neural Overload.
Maybe one for Temporal Manipulation, or Universal, that halves the action point cost of every psi skill but increases their psi point costs by 50%.
A helmet that increases resolve by a fixed number or percentage.
Armour that drains 10 psi at the end of every turn during combat and has amazing DR/DT, but if it loses power then it has no defence or very little defence.
Boots that raise your movement speed by a percentage of your temporal manipulation skill.
A jet ski that lets you use psi powers that don't usually work on water, like forcefield and electrostatic imprint.
A Metathermics headband that prevents friendly fire for allies and neutral parties. Maybe with a button to turn it off and on in-case you want to start combat against someone with it.
Anyway, there's a lot of scope for unique psi items and it would have been really nice to see them. Perhaps there's a good few I haven't found in expedition yet, I'll keep hoping, but otherwise it would be great to see some added or for the ideas to be adopted for Underrail 2.