Can the OPI5 be Configured to Run LCNC?

I don't know what to say. I wrote the image 2 times on nvme and it doesn't boot.

I used the image "Armbian_24.8.1_Orangepi5_bookworm_vendor_6.1.75_cinnamon-backported-mesa_desktop.img" (the one in your link on page 35), and it boots and I can apply rt kernel to it.

The answer lies in the differences between the two non real time images. One boots and the other doesn't.

Maybe it's me but it's not clear to me, the message above means that you can boot now from nvme with the last rt kernel on the image I suggested in the first place?

I can boot Armbian24.8.1 non-realtime. I can install realtime kernel, I can do the link and when I restart it doesn't boot.

It's a bit of a mystery for me. A ftdi adapter could help to give some more information. Maybe firmware is missing or a driver is as module but should be built in. When you boot from the sd-card with the rt kernel, the nvme is still recognized? If so, can you show the output of blkid and of dmesg after boot and lsmod?
dmesg > dmesg-output.txt
lsmod > lsmod-output.txt
blkid > blkid-output.txt

running from sdcard - kernel6.1.75-rt23

I've looked at it but unfortunately can't find what's wrong if it boots from nvme with the other kernel.
You could check when it brings you to the initramfs shell if the nvme is recognized and if the UUID is the same as the one in the boot folder of the root of the nvme.

Maybe someone else a suggestion?

Otherwise it might be better for this moment to keep using the 5.10 kernel until the mainline support is good enough. From 6.12 there is no need to patch the kernel anymore by the way, rt became mainline.