Sigh, sometimes Apple Tech Support and even Geniuses can be useless.
One Tech Support individual on the phone did a remote test of my GPS and said it was fine even though I was deep indoors at home with no GPS reception at all! And she said my gyroscope seems to be working, so the GPS must be fine?!? As far as I know, the gyroscope assists GPS by adding altitude info etc. but its functionality doesn't prove the A-GPS chip is working. Also, the Genius at the store tested my phone using Apple Maps and claimed GPS was working until I explained that we were both in the basement of the store and showed the difference between a stationary circle (location based on Wifi/cell towers) and pulsating circles (GPS reception) - as explained to me by a GPS app developer. I also have serious doubts about what you were told at the Japanese store. i.e. that the Japanese iphone can't handle Verizon.
Using Verizon in the US requires CDMA ,as in the American A1865 model, which I guess is your current model...
(The American A1901 model doesn't have CDMA, hence the warning)
See here iPhone X - Technical Specifications - Apple (this says CDMA is needed for Verizon)
However, the Japanese iPhone A1902 appears to have the required CDMA specs:
- TD-SCDMA 1,900(F)、2,000(A)
- CDMA EV-DO Rev. A(800、1,900、2,100MHz)
iPhone X - 仕様 - Apple(日本) (I know it is in Japanese but just scroll down to the stuff with CDMA)
If the Store is refusing on technical grounds they are likely to be wrong or just giving you B/S.
(they are right about the permanent shutter noise though. It was introduced because Japan has so many perverts https://www.iphonetricks.org/til-you-cant-silence-camera-shutter-sound-on-japane se-iphone-models/)
Having said all this, don't waste any more of your vacation. It ***** you had to pay $120 for a temporary replacement.
And it ***** that they employ people who give us misleading information.
(wow, they even censor the word " s-u-c-k-s". Are we Quakers now?)