After a few months of trial & error I finally got my build to work!!!
What's working: Xcode, Docker, Apple services (iCloud / FaceTime / Messages / etc.).
The only things that aren't working yet are: my on-board wifi/blouetooth card & on-board sound card line-out jack (digital out works fine).
Many thanks to @XNLC for all the attempts to help me out with my stubborn Gigabyte motherboard & kernel panics I was having.
What finally worked for me was the vanilla Mojave guide (viewtopic.php?f=24&t=5902).
I've created the installer, but skipped adding the AMD kernel, then I've used the Clover kernel patches from https://github.com/AMD-OSX/AMD_Vanilla (with some additional patches provided by @AlGrey).
I'm attaching my final config.plist if anyone would need it.
Kudos to @Shaneee & @AlGrey for all that awesome work you did!
Cooler Master MasterLiquid 360 RGB TR4 Edition AIO / 3 x Noctua NF-P12 REDUX 1700RPM PWM
GIGABYTE X399 AORUS XTREME (F5g BIOS)
32GB (4 x 8GB Corsair DDR4 3200MHz C16 XMP 2.0)
PowerColor RX 580 8GB Red Devil Golden Sample
2 x Samsung SSD 970 EVO 500GB M.2-2280
Samsung SSD 850 EVO 250GB SATA
Western Digital Black 750GB SATA III 2.5" (WD7500BPKX)
Seagate BarraCuda 4TB SATA III 3.5" (ST4000DM004)
Operating Systems: macOS 10.14.4 / Windows 10 Pro / Pop!_OS 19.04