After almost 3 very long and frustrating weeks, I finally got my build working. My issue?
IOConsoleUsers: gIOScreenLockState 3, hs0, bs0, now 0, sm0x0
I've tried everything. Installed Catalina, Mojave, High Sierra... all stopped there at first boot.
I noticed something tho: while installing, the gIOScreenLockState 3 had values different from 0. And I could see the GUI and do my partitioning and setup. But after installation, all values for gIOScreenLockState were 0 and it hung there.
So I figured I should copy the EFI folders from the bootable USB (since those seemed to work for install) and overwrite the EFI folder from the installed partition.
I have a Windows 10 dualboot, so I booted up in that and followed these steps to access the EFI partition:
1- Mount the EFI partition to a free mount point:
-- Run command prompt as administrator
-- Type "mountvol X: /s" (without the quotes, X being an unused mount point)
2- Use Explorer++ (Free, Open Source app) to manipulate the files on the partition:
--
https://explorerplusplus.com/
-- Run Explorer++ with administrative privileges
(credit to Dr.Hurt from InsanelyMac.com)
After copying them, I rebooted and Catalina booted right up and I could finish my initial setup.
Everything works! Bluetooth adapter, built-in speaker, ultra-wide display, bluetooth keyboard. Very pleased.
Note: I am using an HDMI only ultra-wide monitor with a DP to HDMI adapter. PC is m93p Tiny, i5-4570, HD4600, 8GB ram, 500GB SSD.
Thank you Gigamaxx.