@justanothernoob the images with "current" instead of "vendor" in the name have very limited hardware support (no HDMI, no sound, etc). You should peek the "vendor" images. Mind I noted to use the images dated 16th of August or post as otherwise your pcie sata connected drives won't work most of the time.
So you should try bookworm_vendor or noble_vendor with xfce,cinnamon,gnome,kde-neon if you want a graphical interface and minimal for serial console/ssh only.
You will only get black screen from HDMI with "current" images, that is expected (the HDMI support is not in the linux kernel, only in linux-rockchip kernel, ie vendor as of yet).
ie the image you told using https://fi.mirror.armbian.de/incoming/prahal/rock-5-itx/archive/Armbian_25.8.1_Rock-5-itx_bookworm_current_6.12.41_minimal.img.xz is such a linux kernel without HDMI support for rock-5-itx.
https://fi.mirror.armbian.de/incoming/prahal/rock-5-itx/archive/Armbian_25.8.1_Rock-5-itx_bookworm_vendor_6.1.115_xfce_desktop.img.xz
has HDMI support.
you should be able to install form serial console with both vendor and current images.
Mind I still need to read about installing RoobiOS on my emmc as sadly my board was shipped with an empty EMMC. So I cannot yet guide you through RoobiOS boot selection.
