Yes, I realized I was using a wrong version of the ISO, after about two cups of coffee and an hour of intense staring at the screen.
Turns out I was just being blind and overthinking the problem....

Thank you both!
Using the ESD file still gives the following error.

C:\Windows\system32>Dism /Online /Cleanup-Image /RestoreHealth /Source:esd:H:\sources\install.esd:1 /limitaccessDeployment...

Custom build for a friend.
OS: Windows 10 Pro, 64-bit
MB: MSI Z170-A Pro
Graphics Card: GeForce GTX 680
CPU: Intel i5 6600K @ 3.50GHz
RAM: 8g

Installed OS through bootable USB, as the build...