Test in the config works fine, but when I launch the game itself, black window opens (with white lines along the top left corner) but only for a few seconds and closes on its own, no error message.

Things tried:
- default settings in config, lowest and highest
- windowed and fullscreen from 640x480x32 to 3840x2160x32
- running as admin and turning off fullscreen optimisation in compatibility tab
- changing ShowAllRefreshRates in Regedit to 0 and 1
- reinstalling DirectX
- adding exception to DEP

i5 11600 + RTX 3070; Win 11

I can confirm, I have the same problem and tried the same options as you.

AMD Ryzen 7 7800X3D 8-Core Processor + AMD Radeon RX 7800 XT
Windows 10 64-bit

also tried:
- disabling intro
- using dgvoodoo2 (the logo appears, so its working in essence, but it still crashes)
- tried renaming KnightShift.exe, KnightShift.ex1, KnightShift.ex2 to something different (like Kopie.exe, Kopie.ex1, Kopie.ex2) -> nothing
- deactivated my internal gpu so that it should only use my (7800XT) graphic-card
- tried the german as well as the english version of the game

the "testing" of graphics works in any case, but the benchmark crashes as well, just like the main game.

edit: i noticed that in the task manager (details) the game uses the KnightShift.ex2

Alright I got it to work, but it's weird and not quite sure why it works.
Maybe someone else can try, to see if it works for them, too?

what I did:
I copied the folder (so that i was like "Knightshift - copy"). And before i even once started the game i made the DEP exception. Then started it and it worked.

Maybe just renaming the folder could help as well?
edit: no it doesnt help, if you rename "Knightshift" it says the game isnt installed properly.
edit2: reinstalling the game and making the DEP exception before doesnt help either, you need to make a copy of the folder I guess. also weird: it seems to get the profile (savefiles) from the "Knightshift" folder still, and not from the "Knightshift - copy" folder. I guess that is a registry thing.
I could also remove the DEP and it stopped working, and once I put em on again it also worked again.

So as of now, you have to use 2 folders of the game (original & copy), then make a DEP exception for the 2 exe files in the copied folder and start the game (from the copied folder).

regardless:
One thing still irks me though. The framerate seems very choppy in the 3D department, scrolling the screen or moving a mouse is smooth.
I tried dgvoodoo2 but that wasnt even necessary since the 3d modells are choppy anyway. I even set the various options to the lowest possible but it still seems choppy. Almost as if the game had low fps or something. And yet, Bandicam (a recording tool i use) shows me 160fps.
Is this normal perhaps? I have a vague memory of it running smoother but that could just be my memory remembering it wrong. ;)