For building TWRP for Xiaomi PocoPhone F1

Works:

• ADB
• Decryption of /data
• Screen brightness settings
• Now UI is very smooth
• Vibration on touch
• Correct screenshot color

First checkout minimal twrp with omnirom tree:

repo init -u git://github.com/minimal-manifest-twrp/platform_manifest_twrp_omni.git -b twrp-9.0
repo sync

Then add these projects to .repo/manifest.xml:

<project path="device/xiaomi/beryllium" name="PainKiller3/twrp_xiaomi_beryllium-new" remote="github" revision="android-9.0" />

Finally execute these:

. build/envsetup.sh
lunch omni_beryllium-eng
mka adbd recoveryimage ALLOW_MISSING_DEPENDENCIES=true # Only if you use minimal twrp tree.

To test it:

fastboot boot out/target/product/beryllium/recovery.img

Here

• Thanks to @notsyncing for the base: https://github.com/notsyncing/android_device_xiaomi_polaris