If anyone in the US is interested in a Mi 11 Ultra, I may be selling mine in another week or two.
My config is:
512GB / 12GB / Marble / Unlocked bootloader with xiaomi.eu 12.5.17 rom / few minor scratches on the screen, nothing too noticeable / few scratches around the charging port which this phone always gets / gel screen protector for the front / glass screen protector for the cameras / clear/white cf skin for the back, but you still see the beautiful marble design / 3 cases / with original power brick.
EU ROM works fine. GPay, banks, Netflix all work ok. Updates via fastboot is simple and easy. Can't help you about band 66. I don't think anyone has managed to enable any extra bands, even with root but I would hope someone from us is reading and can answer.
I ordered mine from Giztop. It was the Chinese version. Giztop had the lowest price and fantastic service. All these outfits are located in Hong Kong, so when they sell you the phone they have to get it first from mainland China (Shenzhen). That's what takes the most time, Once they get it from the mainland, shipping with DHL takes about a week to 10 days. I prefer the Xiaomi.eu rom. It's based on the China, which is always ahead of the Global and EEA roms, version and feature wise. All Google services are baked in and working flawlessly. Updates are quite simple since there's no TWRP for MIUI 13/Android12 yet. You merely download the ROM to your PC and unzip it, give it permission (Windows), then place your phone in Fastboot and connect it to your PC via USB and run the script. There are scripts there for Windows, Linux and Apple (Mac). Shenzhen is currently on lockdown due to COVID-19. So the process will take longer depending on how long their lockdown lasts.