Shadow Pro3 oil pressure gauge looks not so accurate
 

I am using Nutec NC-51 0w-30 engine oil, and the oil cooler is HKS S Type for 86/BRZ.

Attached images are the results measured using two gauges under the same other conditions. I believe in the accuracy of defi as an industry benchmark, so it seems that the measurement results of Shadow Pro3 are not accurate and the price is not cheap. Has anyone done a similar comparison? How is the result?

Do you have the sensor connected in the same location?

Yes, same location, same oil temperature, same RPM ...

Well as you'd alluded to, the sender is likely designed or functioning poorly in one of them. I'd send the one you trust less back for a refund and include your findings to them.

Use the one with higher oil pressure. Car wont care, you will feel better!

Only about 5 Bar in it, probably not that far outside of tolerance on sensors between the 2. Both give you a good indication of the pressure, TBH both are in the ballpark of the pressures I'd expect.