such repo, much nice, wow!

Download / git clone this repository to :
$android_src/vendor/mediatek
or copy vmtk.xml to :
$android_src/.repo/local_manifests/
then simply repo sync your sources

Include both VendorConfig.mk & VendorProduct.mk in your device tree like so :

• BoardConfig.mk :
  include vendor/mediatek/VendorConfig.mk

• device(_product).mk :
  include vendor/mediatek/VendorProduct.mk
  Note: add these lines at the bottom of the mentioned files

Patches located in the patches folder can be applied from the root of your android sources :
. vendor/mediatek/patches/install.sh & . vendor/mediatek/patches/uninstall.sh

WIP: just export your shims in init.mtxxxx.rc for now
Copy & paste these flags in your device tree BoardConfig.mk : (uncomment the flags you need)
#LIBSHIM_XLOG_SYMBOLS :=true
#LIBSHIM_SND_SYMBOLS := true
#LIBSHIM_UI_SYMBOLS := true
#LIBSHIM_GUI_SYMBOLS := true
#LIBSHIM_OMX_SYMBOLS := true
#LIBSHIM_BIONIC_SYMBOLS := true
#LIBSHIM_AGPS_SYMBOLS := true
#LIBSHIM_ATOMIC_SYMBOLS := true

• building TWRP in LOS-15.x tree (temp fix) : patches/optional/0001-TEMP-TWRP-fix-recovery-build-with-f2fs-on-LOS-15.x-t.patch