New build here : https://androidfilehost.com/?fid=8889791610682879690
Kindly TESTED by a owner 
Built with “community” /e/ Docker engine, using v1-pie branch.
NB : just made one change : reverted LOS fingerprint “patch” to Pie, in order to make it work (tested). Repository : https://github.com/BallonLac/android_device_xiaomi_polaris
According to rules it should remain an unofficial build, not a custom one.
roomservice.xml
<?xml version="1.0" encoding="UTF-8"?>
<manifest>
<project name="BallonLac/android_device_xiaomi_polaris" path="device/xiaomi/polaris" remote="github" />
<project name="LineageOS/android_kernel_xiaomi_sdm845" path="kernel/xiaomi/sdm845" remote="github" />
<project name="LineageOS/android_packages_resources_devicesettings" path="packages/resources/devicesettings" remote="github" />
</manifest>
muppets.xml
<?xml version="1.0" encoding="UTF-8"?>
<manifest>
<remote name="muppets" fetch="https://gitlab.com" />
<project name="The-Muppets/proprietary_vendor_xiaomi" path="vendor/xiaomi" remote="muppets" />
</manifest>
Build script
docker pull registry.gitlab.e.foundation/e/os/docker-lineage-cicd:community
docker run \
-v "/srv/src:/srv/src" \
-v "/srv/zips:/srv/zips" \
-v "/srv/logs:/srv/logs" \
-v "/srv/ccache:/srv/ccache" \
-v "/srv/local_manifests:/srv/local_manifests" \
-e "BRANCH_NAME=v1-pie" \
-e "DEVICE_LIST=polaris" \
-e "OTA_URL=" \
-e "REPO=https://gitlab.e.foundation/e/os/releases.git" \
registry.gitlab.e.foundation/e/os/docker-lineage-cicd:community