Okay, great news! shikigva=28 solved everything! I'm posting my configs and files and hope this will help someone.
VDADecoderChecker: work!
MacX hardware acceleration: work!
FCPX & Compressor HEVC 8-bit encode: work!
IOVARendererID & SubID: present!
iTunes HDCP content: don't crash and work!
My main hurdles were
1. Make sure Lilu and dependents load, placing them in /L/E and added lilufriends.kext solved it
2. ig-platform-id must be correct
3. Find correct value for shikigva
MB: Gigabyte Aorus Z370 Gaming 3
CPU: iCore 7 8700
Graphics: Gigabyte Aorus GTx 1080 Ti Xtreme
macOS 10.13.2 w/ Supplemental Update
nVidiaWebDriver 378.10.10.10.25.104
Clover v2.4 r4330
BIOS Integrated Graphics set to enabled, DVMT 64MB, DVMT Max set to Max and Primary display PEG DP1
FakeSMC.kext 6.26-322-g1b20eab7.1765 in CLOVER/kext/Other
Files in /L/E
Lilu.kext 1.2.1
LiluFriends.kext 1.1.0
NvidiaGraphicsFixup.kext 1.2.2
Please note that I've removed serial number, SMUUID and board-serial number from my config file.
Hope this will help someone, and thanks again for everyone's help, especially
shuhung's suggestions.