I've found information that implies IOT Enterprise is binary identical to regular Enterprise, but I'm having some trouble with my answer file that tries to call on Embedded features.
Specifically, I'm getting an error in the logs that it can't find a namespace for Microsoft-Windows-Embedded-EmbeddedLogon and Microsoft-Windows-Embedded-ShellLauncher. I've included what I believe is the relevant section of the logs below.
2019-04-29 10:02:03, Warning [setup.exe] SMI data results dump: Source = Name: Microsoft-Windows-Embedded-ShellLauncher, Language: neutral, ProcessorArchitecture: amd64, PublicKeyToken: 31bf3856ad364e35, VersionScope: NonSxS
2019-04-29 10:02:03, Warning [setup.exe] SMI data results dump: Description = Unable to find a component matching the given namespace.
2019-04-29 10:02:03, Warning [setup.exe] SMI data results dump: Source = Name: Microsoft-Windows-Embedded-EmbeddedLogon, Language: neutral, ProcessorArchitecture: amd64, PublicKeyToken: 31bf3856ad364e35, VersionScope: nonSxS
2019-04-29 10:02:03, Warning [setup.exe] SMI data results dump: Description = Unable to find a component matching the given namespace.
The XML in my answer file is as follows:
<settings pass="specialize">
<component name="Microsoft-Windows-Shell-Setup" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS" xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<ComputerName>*</ComputerName>
<Display>
<ColorDepth>32</ColorDepth>
<DPI>96</DPI>
<HorizontalResolution>768</HorizontalResolution>
<RefreshRate>60</RefreshRate>
<VerticalResolution>1024</VerticalResolution>
</Display>
<Themes>
<ThemeName>Viper Theme</ThemeName>
<DesktopBackground>%WINDIR%\Web\Wallpaper\SpectrumMedicalBackground.jpg</DesktopBackground>
</Themes>
</component>
<component name="Microsoft-Windows-Embedded-EmbeddedLogon" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS" xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<AnimationDisabled>1</AnimationDisabled>
<HideAutoLogonUI>1</HideAutoLogonUI>
<NoLockScreen>1</NoLockScreen>
<UIVerbosityLevel>1</UIVerbosityLevel>
</component>
<component name="Microsoft-Windows-Embedded-ShellLauncher" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="NonSxS" xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<Shell>C:\Launcher.exe</Shell>
<DefaultReturnCodeAction>3</DefaultReturnCodeAction>
</component>
</settings>
UPDATE: I found a program called "ShellLauncherConfig.exe" in a directory that matched the "Microsoft-Windows-Embedded-ShellLauncher" name and tried to run it from powershell. I got an error that the executable is not a valid application for this OS platform.
../sources/sxs
directory within a Windows image. Your error is basically telling you, Windows is not aware of which feature you want to use because it does not recognize or find those two features in order to enable them.