All credits go to the Lawnchair Team.
Quickstep enablement is done with the help of QuickSwitch Magisk module made by Skittles9823.
1. Clone this repository to your AOSP build root's
git clone *link -b *branch vendor/lawnchair
* example
2. Import vendor/lawnchair/lawnchair.mk
$(call inherit-product, vendor/lawnchair/lawnchair.mk)
* inherit-product$(call inherit-product-if-exists, vendor/lawnchair/lawnchair.mk)
* inherit-product-if-exists
3. Remove existing launcher from the build https://github.com/psionicprjkt/android_vendor_lawnchair/blob/cca8061f88464fa4136248bd2449ebe20a374d82/Android.bp#L10