Hello and God bless. Just a report. Apparently I have too-new hardware. As a result, Slackware 15 install was very difficult, and X still will not run.

I have been a Slackware user since version 13.
Brand new computer:
Dell i-3910
NVME ssd
Intel 12 Gen i5-12400
Integrated Graphics Card Intel 730 (using hdmi output)

I want to run this machine as dual boot with Windows. Partitioning potential linux partitions via Windows Disk Manager proceeded flawlessly: made potential partitions for root, swap, and home.

(1) The current problem is that X WILL NOT RUN. For instance, even liveSlack will NOT boot into its GUI at all. It never gets to the Gui. All I can get is the command line.

Regular install also will not 'startx' In all cases, including liveSlack, the Message from /var/log/X*.log is:
vesa: Refusing to run on UEFI

By contrast, lubuntu-insall, (and Windows) for instance, have no problem presenting a GUI. Nothing wrong with the hardware.

(2) NVME format fail.
fdisk and cgdisk in Slackware 15 install could not format the new 'raw' nvme partitions I made via Windows disk manager. They sort-of-kind-of did, but 'fdisk -l' never showed linux partitions on the nvme drive, however many times I said, eg., 'fdisk /dev/nvme0n1p4' and wrote a Linux or (swap) partition to it. At any rate, when I would enter 'setup', it did not recognize the partitions. Install could not proceed.

THE FIX!? I finally resorted to lubuntu-install, just for it to see and format the 'raw' Windows partitions as ext4, which the current lubuntu-installer did fine and instantly.

After that, but ONLY after that, would Slackware-install see the NVME partitions and install onto them.

(3) After install, elilo did not work. It froze and did not load Slackware.

I finally installed GRUB manually from CLI. Grub was able to load Slackware. From there, on the CLI, I did the normal slackpkg update/install-new/upgrade-all.

However, X still will not run.

I do not want to give up on Slackware 15, but for the moment, X refuses to run and I cannot proceed.

What kernel do you boot ? Huge ?
I bet you could try with proper initrd or try the slackware-current kernel : download the sources, grab the config file provided, compile, copy, build initrd, update grub and try.

Slackware-current install (01-23-2023) solved the problems. elilo now works and boots Slackware, and startx successfully gives a GUI.