(Images are hosted on catbox.moe with a total size of 1.9MiB - your data plan will be fine)

Following Android docs, unlocking a bootloader should be as simple as enabling that option in developer settings, and issuing fastboot flashing unlock command in the bootloader.

But not all manufacturers like that.
So, here's the fuckery I went through.

Obtaining Mi Unlock tool

That one comes from here: https://en.miui.com/unlock/download_en.html
Which also links to these steps: https://new.c.mi.com/global/post/101245

First run

And we need an account.

Account creation

Since I'll need it on the phone as well, I decided to create the account from there.

I've used e-mail + password for sign-up.
There was also a confirmation e-mail sent to me, nothing special so far.

Logging into Mi Unlock - First roadblock

After entering e-mail + password, it fucks up with a blank verification page.

This was also reported by someone on XDA, with a solution to update.

Mi Unlock updaten't

I've tried both with and without a VPN, no luck. Some people reported the same issue when I searched around.

Workaround - QR code login from phone app

Of course, this needs more private data - a phone number, because why not?
And of course, it also does not fucking work.

Entering phone number in browser

This worked. But the phone app still didn't like me.

Do notice the "attempts remaining", this will be important later.

Workaround - QR code: Electric Boogaloo

The QR code actually contains a URL, so let's open it in a browser.

Well, fuck. Let's do that again.

And we are in.

Binding phone to Mi Account - More data collection

I thought the problem above (gray unlock button) was the phone not yet being "binded" to the account, so I skipped to this step.

So I inserted a SIM card, but they didn't lie. It really requires mobile data. I even tried Bluetooth network as someone else suggested.

This was a bit of a problem as I used a burner SIM with no data.
Random data eSIM on removable eUICC (9esim V3) was able to help with this.

Back to Mi Unlock - SMS rate limit

It seems there's a limit of 3 SMS codes per 24 hours outside of China.

Back the next day - Episode: Windows drivers

The Mi Unlock tool should include the USB drivers, but something's fucked up there.

Someone on XDA mentioned one of the 2 driver files can be renamed to the required filename, because let's ship a broken tool.

So I did that:
This now shown Windows installation prompt.

But why yes, it did not work.

So, I downloaded the drivers from Google, and tried following their instructions.
So that did it, right? Nah. Windows wouldn't find the driver.

The solution was following someone's Reddit comment.

Choose the option that says 'Let me pick from a list of available drivers on my computer', then browse to and select the file named android_winusb.inf. From there, you'll be able to choose 'Android Bootloader Interface' to install.

For comparison, on something like Arch Linux, this is a matter of extremely hard and time-consuming sudo pacman -Sy android-tools. /s

Reaching the fruit

The device is finally recognized.

And there we go.

And the final step:

I used to love unlocking phones and flashing ROMs, but that era is basically over. I hate it.

God that is just awful.

Thank you for sharing this journey as I'll be taking it soon to unlock a tablet. 🫡

It's been a few years now that Xiaomi must be avoided for these reasons. Your are even lucky that your phone can be unlocked at all, since all latest models are not unlockable full stop.

I purchased a Nothing phone and couldn't be happier. De bloated android stock, and fully offline unlockable bootloader, no phone home required.

Motorola has an easier process but you still need to make an account and use an online tool that could go away anytime in the future

Don't buy Xiaomi.

I had a similar experience when I unlokckdd my poco x3 three years ago. Besides all this crap you went through I also didn't have a windows machine so I had to dig for a Linux solution, unofficial obviously. I bought a Motorola phone last month and I'm really hoping they have a lineage port to it ASAP. Can't stand the way android got enshitified

I've used a Windows VM with USB passthrough.

It was €12 used ¯⁠\⁠_⁠(⁠ツ⁠)⁠_⁠/⁠¯

They also have plenty of scare words:

MOTOROLA STRONGLY RECOMMENDS AGAINST UNLOCKING THE
BOOTLOADER AND/OR MODIFYING OR ALTERING A DEVICE'S SOFTWARE OR
OPERATING SYSTEM. DOING SO CAN HAVE UNINTENDED, UNFORESEEN, AND
DANGEROUS CONSEQUENCES, SUCH AS RENDERING THE DEVICE UNUSABLE,
VIOLATING APPLICABLE LAWS, OR CAUSING PROPERTY DAMAGE AND/OR BODILY
INJURY, INCLUDING DEATH.

And don't allow you to sell the phone later on:

Devices that have been unlocked are for your personal use only. Once you unlock
the device, you can only use it for your personal use, and may not sell or otherwise
transfer the device

I'm surprised they didn't require you to wait a couple of days for the unlock

reading that warning above, could it be it would have disallowed unlocking if a former owner added their Mi account?

Which one?

the 3rd image after "Binding phone to Mi Account - More data collection"

Possibly it wouldn't even be usable at all. I've found some images of Xiaomi devices locked by factory reset protection based around Mi account.
It also warned me to remove the account from all devices before deleting it, as they otherwise "wouldn't work properly".