So… I dug around in the system HW info via an app on my global/EU unit.
The (NFC) chip is listed as “st21nfc” NFC controller (STMicroelectronics). If you check the datasheet for the ST21 series, they are high-end chips that natively support the NFC-F/FeliCa standard.
And when you dig around the system features you can find "android.hardware.nfc.hcef’ (Host Card Emulation FeliCa).
So basically the phone is able to use the FeliCa NFC feature (the hardware and most of the software* is all there), which on non JP units allows you to maybe read Suika cards as in reading the balance maybe (I think you can do that?) but the phone itself can’t act as one because of how Sony designed the spec.
Now as to the reason why it doesn’t work (and not even flashing JP firmware will help).
So how the spec works is that each phone has, to my understanding, a set of unique license keys that are permanently burned/written into a special secure element/chip on the phone (which all the models seem to have).
So how I believe it works simplified: Manufacturer (Nothing) pays Sony -> The manufacturer gets the keys (which are maybe even tied to the HW IDs of the specific phone) -> Keys are burned into the Secure Element at the factory (probably even before the OS is flashed)
And on Global Units they just dont get any keys so the Secure element stays empty.
TL;DR: You can’t flash Japanese firmware to fix this because you can’t “software update” a missing license key into a write-protected security chip. The hardware is there, but the “ignition key” if you will was never installed at the factory.
