The device currently only works under outdated pmaports using linux 5.12.8 which is missing important components and is pending sdm845-mainline/linux!102 to port on Linux 6.11
The relevant Mi8 family with SDM845 chips has the following devices:
Xiaomi Mi 8 (xiaomi-dipper)
Xiaomi Mi 8 Pro (xiaomi-equuelus)
Xiaomi Mi 8 Explorer (xiaomi-ursa)
The phones appear to be nearly identical and apparently all use the same mainboard, but there are differences:
Dipper has bigger battery and different fingerprint sensor (mounted at the back while equuelus and ursa have it under the screen)
A special case might be with xiaomi-ursa, which is a device with transparent back that have a fake plastic components as from available information it was used only in China for early adopters as a way to develop the firmware and then ~3 months later the dipper and equuelus were released to the public with ursa having it's firmware flashed on equuelus and sold in the rest of the world as Xiaomi Mi 8 Pro with titanium transparent back.
The motherboard in ursa is not always the same and appears to be an earlier prototype which might have hidden hardware issues. Additionally the firmware for ursa is china-only and appears to have more features.
Reportedly the Xiaomi Pocophone F1 (xiaomi-beryllium) is allegedly built from ursa's designs to be very similar, but has different mainboard and devices.
Partition map
Observed to be the same on Dipper and Ursa, while probably same on Equuelus.
equuleus:/ # ls -la /dev/block/bootdevice/by-name/
Kreyren (Notes: Ursa in Mint Condition, used for developing NixOS compatibility)
Mertoalex (Notes: my mom's phone, Equuleus (mi 8 pro), LineageOS 22 is installed.)
How to enter flash mode
Bootloader Unlocking
Do NOT attempt to bypass the unlock key via MiUnlockToolv2 as Xiaomi patched the vulnerability on their servers and when attempted they might make you wait longer before it allows you to unlock. In some cases you might end up with a bricked device that can only be unlocked at Official Xiaomi Store or their Authorized Technician for a fee or ~40 EUR assuming you have a proof of purchase.
Like other Xiaomi devices, the user will have to acquire the bootloader unlock key: https://en.miui.com/unlock
The device will not unlock if the device isn't 7 days old (from the time when your device connects to internet and powered on, and linked with Mi Account)
Recovery mode
At any state of the device hold Volume Up and Power button until the recovery screen shows up.
Flashing (Download, Fastboot) mode
Same as recovery, but this time hold the Volume Down and Power keys.