First things first, put my displays back on the USB hub. Pray for me =p
Both plugged back... DP working, HDMI not.
Let's see, my current .nvidia-settings-rc is this one:
#
# /home/johnny/.nvidia-settings-rc
#
# Configuration file for nvidia-settings - the NVIDIA Settings utility
# Generated on Sun May 21 22:56:00 2023
#
# ConfigProperties:
RcFileLocale = C
DisplayStatusBar = Yes
SliderTextEntries = Yes
IncludeDisplayNameInConfigFile = No
UpdateRulesOnProfileNameChange = Yes
Timer = PowerMizer_Monitor_(GPU_0),Yes,1000
Timer = Thermal_Monitor_(GPU_0),Yes,1000
Timer = Memory_Used_(GPU_0),Yes,3000
# Attributes:
[DPY:HDMI-1-0]/Dithering=0
[DPY:HDMI-1-0]/DitheringMode=0
[DPY:HDMI-1-0]/DitheringDepth=0
[DPY:HDMI-1-0]/ColorSpace=0
[DPY:HDMI-1-0]/ColorRange=0
[DPY:HDMI-1-0]/SynchronousPaletteUpdates=0
[DPY:DP-1-0]/RedBrightness=0.000000
[DPY:DP-1-0]/GreenBrightness=0.000000
[DPY:DP-1-0]/BlueBrightness=0.000000
[DPY:DP-1-0]/RedContrast=0.000000
[DPY:DP-1-0]/GreenContrast=0.000000
[DPY:DP-1-0]/BlueContrast=0.000000
[DPY:DP-1-0]/RedGamma=1.000000
[DPY:DP-1-0]/GreenGamma=1.000000
[DPY:DP-1-0]/BlueGamma=1.000000
[DPY:DP-1-0]/Dithering=0
[DPY:DP-1-0]/DitheringMode=0
[DPY:DP-1-0]/DitheringDepth=0
[DPY:DP-1-0]/DigitalVibrance=0
[DPY:DP-1-0]/ColorSpace=0
[DPY:DP-1-0]/ColorRange=0
[DPY:DP-1-0]/SynchronousPaletteUpdates=0
[GPU:0]/GPUPowerMizerMode=2
there is no /etc/udev/rules.d/80-nvidia-pm.rules, but there is a 90-nvidia-prime-powermanagement.rules by that same directory:
# Enable runtime PM for NVIDIA VGA/3D controller devices on driver bind or device add
ACTION=="bind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", TEST=="power/control", ATTR{power/control}="auto"
ACTION=="bind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", TEST=="power/control", ATTR{power/control}="auto"
ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", TEST=="power/control", ATTR{power/control}="auto"
ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", TEST=="power/control", ATTR{power/control}="auto"
# Disable runtime PM for NVIDIA VGA/3D controller devices on driver unbind
ACTION=="unbind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", TEST=="power/control", ATTR{power/control}="on"
ACTION=="unbind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", TEST=="power/control", ATTR{power/control}="on"
and indeed, just like the OP on that reddit post, my xrandr --listmonitors shows only...
xrandr --listmonitors
Monitors: 1
0: +*DP-1-2 2560/798x1080/334+0+0 DP-1-2
the OP also mentions mkinitcpio, but when I try to install it via pacman, I get a warning of conflict with garuda-dracut-support... not quite sure if I should?
reading on Dracut | Garuda Linux wiki - will be back
I think doing a dracut-rebuild broke something... I'm such on the "loading initial ramdisk" screen 
This is weird. My Bluetooth speaker is connected to the computer, and this only happens after logging in... The three displays are turned on, but they all show the same "loading initial ramdisk" screen o.o
Nothing on tty1 or tty2, but tty3 gives me login prompt.
But if I X on tty3, it dies like the rest
I feel like someone's gonna kill me for this, but it's the best I can do right now...
Looking into Garuda shows nothing after reboot and that's a dead-end because at least they have GUI...
No startx either...
and we're back from the snapshot backup.