Nevermind, got it working with using setupcomplete.cmd instead.

Thanks for the help so far, but ended up scrapping the whole disk format portion.

Now I have two differend files, one autounattend that only sets some language settings and skips Eula.
This works...

Ah I see. I was just following the setup we currently use for windows 2019, tho with MDT.
I'l try find a unattended file and just run that.

For fun I tried making a new unattended file from...

That was a sneaky one, thanks. Tho changed it, but still no go. This is my current xml file. Now it takes ages to boot and when entering setup it will just reboot. Might be something missing?
...

I'm pulling my hair over making an autounattend.xml file. Tried adding one piece at a time to see where the file stops working, but cant figure out what is wrong.
The ISO I try to make a...