Is your installer up to date? There's a new Win 11 22H2 version of the installer. I'm thinking that there's maybe something missing in older Windows that's needed for Z790.
Also, if the board is new, did you do a clear CMOS then load optimised defaults? My board (different platform, not specific to Z790) failed to initially POST due to something odd about the CMOS out of the box. A quick clear followed by load optimised brought it to life. Just in case there's some weird setting lurking in there.
I was just thinking that you might be able to install Linux - maybe Ubuntu or similar. From there, you might be able to run some diagnostics and get some more information as to why Windows isn't happy...
You could also just boot to a live Linux USB - you wouldn't even need to install it.
I wouldn't even know where to begin doing that, and know what to look for.