@rinigus, it is excellent indeed.
Continued list:
* both IMEIs (correct) are shown under Settings > Information > About
* ssu s gives UID equals first IMEI correctly too
* ssu s gives device model: "Xperia XZ3 (h9436 / h9436)"
* GPS is quite quick with and without support
So seems good to go for official registration.

And I am ready for testing next builds as outlined.