I haven't looked to verify on my engine, but here are photos pulled from another site pointing at that port. Author acknowledges that he didn't pull the plug out to check, but others had and no oil came out, so there was a question on whether this was actually a plug into a galley or not.

 

https://www.cobaltss.net/forums/2-0l...nstall-273259/

From Cobalt SS site.

 

Oil pressure sensor above the starter, I don’t believe this photo to be an LNF engine

In your posted photo, it’s there just barely visible to the left of the knock sensor

 

That site is where I'm finding some of the information.. some good, some bad :-)

 

I know, plenty of photos, few explanations of what your looking at!
That plug under the oil cooler might be in a coolant passage, it might be in an oil return passage, no pressure just cooled oil headed for the oil pan internally. It might not be pressurized at that point. But then again it is close to the oil pressure sensor!

 

What is wrong with the existing port? If there is a tight spot for a Tee a short pipe would fix it.

 

Here is the sensor, it lives behind the starter and solenoid there might not be enough room back there. I couldn’t find a photo online to confirm the space back in there

 

Oh, nothing wrong with that port other than a lack of space. At one time someone on the Cobalt forums was making a nice, compact remote T block from aluminum and a short braided line from the sender hole. He's not doing those anymore.. nothing a good machine shop couldn't make up if one was inclined :-)

 

A 2 inch piece of threaded brass pipe and a brass Tee from Home depot would take everything out of the cramped quarters.
1 sensor straight out the other at 90 or 45.
I bet a bit of braided brake hose has the same pipe threads.
not to scale

 

Thinking on options. You won't find an M12x1.75 nipple at the Home Depot, but you can get an adapter from AutoMeter and Home Depot out from there...