What is this??

That's the front TOW HOOK. It's designed to screw into the front bumper to assist a flat bed tow truck in reeling your car up onto the flat bed!
Many times lazy tow drivers just want to throw hooks and chains on yer car and that's how front bumper damage occurs!

If I recall there are screw points on diagonal locations. Left side as you look at front or rear bumper.

Thanks for the ID - so that makes sense why there is a 2" cutout with a guard over it on the passenger side of the front bumper. Mystery solved. Makes sense it was in the tire mobility kit - if you're looking to repair a flat tire, you're gonna need a tow - thanks Kia (and pretty much every other PHEV hybrid car manufacturer) for not having room for a doughnut.

No spare in Niro PHEV

As a 70 year old on my 20th car, this bothered me too, initially. But with 5 year 60,000 mile roadside assist (or $8/yr on my car insurance after), and the flat tire needing to be repaired/replaced quickly anyway, not sure that a space saving spare is that useful any more. With a doughnut, all it is going to do is get you to a tire store. Which the fix-a-flat or a tow is going to do. The days of a matching full sized spare that you can put on and continue on your way and deal with the flat whenever (unless you are driving a full size truck/SUV) are over.

The problem is that you could get a flat somewhere in the mountains where cell phones don't work, (heck, our dearest AT&T Galaxy Note seldom works in our house here in Paradise, CA ) and even if you get a signal, the closest tow truck might not arrive for an hour or two. I am 72 but on our Kona I can throw on the spare (original equipment) in less than 20 minutes and be on my way.

Spare tires are also good for getting you to where you are going. Then the tire fix can be done on your schedule, not the road hazard's schedule (and the tow truck).

I recently had to do just that in my last car, but first time in 15 years. Happy to try towing as I am semi-retired, but even when working, I don't commute by car. Have AAA in addition to Kia - also have a road hazard warranty at a nationwide tire chain. That is where I will point the tow truck (not sure if I can do that with Kia's service).

There is room for a spare. I think you can also fit a full size spare as well. There is a limited spare accessory https://kiastuff.com/kia-niro-spare-tire-kit-m015/

Are you sure that the tire will fit a 2018 PHEV?
The sellers don't mention PHEV comparability maybe because so few have been delivered.

The PHEV does not have any storage room for a spare tire or doughnut spare under the cargo floor - that space and lovely tray in the Hybrid is filled with more battery cells in mine. Maybe room for a spare water bottle