Non-specific install.wim directory failing to find wim...

[Ge-koh]

I have a working Windows build USB made to install a cleaned up version of 25H2 (built as a VM in HyperV). However, the unattend.xml points directly to D:. It works in most cases but some device don't assign D. So, I've been trying to get a version working which doesn't point to a specific drive assignment. At first I couldn't get past a Windows 11 Setup error (0x80070490 - 0x4002C). I have a version that gets me to the Setup screen where I can select the installation location and it installs Windows but not using my custom install.wim. Every change I make either breaks the setup or fails to install the wim.

It's getting pretty darn frustrating...

Can anyone help?

The working D:/ version is:
<?xml version="1.0" encoding="utf-8"?> <unattend xmlns="urn:schemas-microsoft-com:unattend" xmlns:wcm="http://schemas.microsoft.com"> <settings pass="windowsPE"> <component name="Microsoft-Windows-Setup" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS"> <ImageInstall> <OSImage> <InstallFrom> <Path>D:\Ventoy\Windows\Wim\install.wim</Path> <MetaData wcm:action="add"><Key>/IMAGE/INDEX</Key><Value>1</Value></MetaData> </InstallFrom> </OSImage> </ImageInstall> <UserData><AcceptEula>true</AcceptEula></UserData> <RunSynchronous> <RunSynchronousCommand wcm:action="add"> <Order>1</Order> <Path>reg.exe add "HKLM\SYSTEM\Setup\LabConfig" /v BypassTPMCheck /t REG_DWORD /d 1 /f</Path> </RunSynchronousCommand> <RunSynchronousCommand wcm:action="add"> <Order>2</Order> <Path>reg.exe add "HKLM\SYSTEM\Setup\LabConfig" /v BypassSecureBootCheck /t REG_DWORD /d 1 /f</Path> </RunSynchronousCommand> </RunSynchronous> </component> </settings>

The version that installs but doesn't use the install.wim is:
<?xml version="1.0" encoding="utf-8"?> <unattend xmlns="urn:schemas-microsoft-com:unattend" xmlns:wcm="http://schemas.microsoft.com"> <settings pass="windowsPE"> <component name="Microsoft-Windows-Setup" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS"> <ImageInstall> <OSImage> <InstallFrom> <MetaData wcm:action="add"> <Key>/IMAGE/INDEX</Key> <Value>1</Value> </MetaData> </InstallFrom> </OSImage> </ImageInstall> <UserData> <AcceptEula>true</AcceptEula> <ProductKey> <Key>VK7JG-NPHTM-C97JM-9MPGT-3V66T</Key> </ProductKey> </UserData> <RunSynchronous> <RunSynchronousCommand wcm:action="add"> <Order>1</Order> <Path>reg.exe add "HKLM\SYSTEM\Setup\LabConfig" /v BypassTPMCheck /t REG_DWORD /d 1 /f</Path> </RunSynchronousCommand> <RunSynchronousCommand wcm:action="add"> <Order>2</Order> <Path>reg.exe add "HKLM\SYSTEM\Setup\LabConfig" /v BypassSecureBootCheck /t REG_DWORD /d 1 /f</Path> </RunSynchronousCommand> </RunSynchronous> </component> </settings>

What am I missing?
FYI - I've tried two different setups of USB. One with everything in the root and an autounattend.xml (the non-working version) and another with the ISO in the root and then x:\ventoy\windows\win directories with a ventoy.json and the wim and xml in their appropriate directories (works but locked to D:).