Have you tried adding it to a mounted install.wim? You would use the same code provided except change DISM /online to DISM /Image:<path to mounted wim>.
I haven't but I'll give it a try as I'm installing through WinPE anyway. Update: Dism fails Offline with v1.2.7: I tried an earlier v1.2.4 & Dism completed the operation. When I boot into Windows it wasn't listed as installed. When I searched for Nahimic I found folder: Code: C:\Program Files\WindowsApps\DeletedAllUserPackages\A-Volute.Nahimic_1.2.4.0_neutral_~_w2gh52qy24etm
wow I didn't realize that v1.2.7 of Nahimic 3 recently came out. wahahaha - using dism.exe to install the Nahimic 3 uwp app w/out MS store requires the corresponding *_License1.xml file - good luck trying to find one for the Nahimic 3 app or maybe ask alanfox2000 on how to install Nahimic 3 offline
The v1.2.4 that Installed offline does include the License1.xml file. I added this to dism: I see @alanfox2000 has "DISM_Install.bat" which looks just like what I've already tried anyway. If I wasn't trying to Sysprep the machine there wouldn't be an issue...
not only that Flipp3r, without an active internet connection to download the A-Volute.Nahimic.zip file after Nahimic3 uwp installation, the Nahimic 3 UWP will not work. I realized the A-Volute.Nahimic.zip file gets downloaded onto the \ProgramData\A-Volute\Archives\ folder and the DLL files from that ZIP file are supposed to be extracted onto the \ProgramData\A-Volute\A-Volute.Nahimic\ folder. I also sometimes have to manually extract all files & folders from the NH3ProductSettings.cab file from the Realtek UAD driver onto that \ProgramData\A-Volute\A-Volute.Nahimic\ folder, which will make the NahimicSvc32.exe and NahimicSvc64.exe files run [as I checked these files listed in Task Manager] and then the Nahimic 3 UWP program will actually run and recognize the onboard Realtek audio device The current version of Nahimic 3 from the Microsoft store is version 1.2.6 as I obtained the A-Volute.Nahimic_1.2.6.0_neutral_~_w2gh52qy24etm.appxbundle file a few days ago and does require an internet connection to silently download the A-Volute.Nahimic.zip file after installation. v1.2.7 seems to be either a beta was pulled from the MS store and v1.2.6 was offered in its place. screenshot of Nahimic 3 UWP app v1.2.6 running on my Gigabyte board using 8578 UAD driver