I work also in Germany and i was pretty sure it was dropped to 16 (checking web it was till 2020, now back to 19%), with covid my trips to Germany dropped a lot=).Nah.. is 19% in Germany , then import taxes on top . You'll be with all taxes you pay and shipping around 27 to 29 % , and you forgot the charger , if I buy in china I have to buy the charger extra. Also your calculation doesn't include fees Xiaomi has to pay for EU and Germany licenses and regulations.
You are looking at USA price without considering that VAT is not included (in the USA almost every time you see a price, it's without VAT, even on shelfs in the supermarkets), so you have to add VAT (which change not only in ever State, but even on different city). In example i calculated iphone 13 512GB, the difference was 9% without VAT, in your example is 999$/852€ USA without VAT and in Germany is 965€, which is 13% of difference between both prices. We(EU) don't have duty taxes on smartphones. All cost that you also considering are cost everyone have to pay, my thought was only about price % (not price themselves).
Thank you for lock/unlock explanation, will think about it - pity no china trip is programmed, i like very much marble theme and i need 512 version (i have note 9 with 512 and i'm even using sd card.