I am unclear as to what the problem is. I do know this. There are no proprietary video drivers for Intel Iris Xe graphic adapters. They are not needed. The i915 driver is built into the Linux kernel.
I have the same driver on my system with Intel UHD graphics.
Why are you editing Grub to “nomodeset?” That is sometimes needed to get the Ubuntu ISO image to load. It should not be needed with Intel graphics. With Nvidia, may be.
With nomodeset you prevent the graphic drivers from loading. Hence, the reboot to a black screen.
How well does Ubuntu run in TRY Ubuntu mode. The TRY mode does not use proprietary video drivers.
What do you mean when you say: “Installing works well?” In my mind an installation works well if I end up with a satisfactory working operating system.