If you want updates, you will have to flash a Cn rom in EDL mode (not free) but you will not be able to install a Global.
Best solution is to return the phone to your "certified "seller.
Xiaomi set to make its own mobile chip
Xiaomi Corp (小米) is preparing a mobile processor designed by its own smartphones to reduce its dependence on foreign suppliers Qualcomm Inc and MediaTek Inc (聯發科).
The decree comes from the official government website.
Here is what is currently happening with old MIU devices that have already been unlocked:
Redmi note 7 pro:
With a bypass
14 Cn devices were already unlocked only using a paid third-party service, but for some time now it no longer works.
https://xiaomitime.com/hyperos-bootloader-unlocking-no-more-available-between-china-and-global-17237/...
Extract modem.img from newer firmware(EEA)
https://xmfirmwareupdater.com/archive/firmware/garnet/
Try with this fastboot CMD:
fastboot set_active a
fastboot flash modem_ab modem.img
fastboot reboot
I don't know why the cloud is still working, but I remember having an orange banner about this shutdown.
Global are still unlockable but with difficulty, for the 15 in hyperOS2 I don't know.