Installed FO4 and when trying to run setup have this message "Video Hardware Not Detected". Manually set to ultra and 3440x1440 resolution in ini file but no effect. Picture is like 8000x600 on ultrawide fullscreen. Any ideas?
My HW - RTX3080, i7 9700k

I also got this message, but was able to set all relevant settings when clicking "OPTIONS". There you can set things like AA, resolution and aspect ratio (when using Windowed Mode, Borderless). When clicking "Advanced", you can fine-tune even further.

I don't know why that does not work for you. But that said, I only use a 1080p monitor, so I have no idea if this works for untra-wide screens.

It will not detect recent hardware, because its database lacks information on them. If a Bethesda game cannot detect your video hardware though, you're either not running it anyway because it's so extremely out of date, or you're well over spec and can probably maximize all settings safely. In your case however, of course, turn off Weapon Debris. Any NVidia GPU from 15xx series onward crashes using that setting. Hoping the next gen update also updates to use the new API NVidia introduced, so it works again.

Thank you everyone for advises, I discovered that there is another ini file located in my docs/my games directory which actually matters, not the one in the game directory!

Make sure to clear out any old steam folders with settings for it in my games/Fallout4(GOTY). May be a few other folder locations as well.