A Value for Money!
Hi there, I bought the device about a month ago. It was delivered quickly and as promised with the charging adaptor included (free of charge) so that the charging brick can be plugged in the EU socket. The velocity of charging is amazing, btw! In contrast to the European version, in the box there was also a pretty nice case (instead of plastic cards welcoming you to the "Oneplus Club" as is the case in Europe/the U.S.) If you are interested, you can see unboxing & full review of the Chinese model on YT by Tech Mishka, the link is already here in the review section, in the one named "Great Phone and Great Value!"
Giztop covered any customs duties as promised, probably via the IOSS account as described on their site. The price incl. shipping costs was more than 25% lower than the cheapest available price of the international version of the phone in my country (CZ). The device is equipped with Oxygen OS, i.e. all relevant languages are available, no regional lock. I believe the OS updates will be delivered regularly to the phone (but don't know yet for sure, it's still relatively new and I bought it as a gift). Banking apps seem to work on it as well. However, Android Auto and eSIM probably won't, but this doesn't bother me.
To sum up, the cellphone performs as expected and the giftee enjoys using it very much!
If you consider buying from Giztop, bear in mind both advantages and disadvantages of buying a Chinese version of a device.
Pros - you most probably get from Giztop exactly what they promised you and at a significantly lower price than available in the EU ($699 + shipping in my case vs $992 local price for 16/512 GB variant).
Cons - you buy a Chinese version made for sale in Mainland China only and with the warranty good only there as well. Thus, if your phone happens to break even if it is still under the warranty provided by Giztop, you will be required to send it to China for repair. That may prove lengthy and requiring you to pay additional costs.