EDIT: as a fyi note, although the Devuan installer uses the debconf installation principle, which is the same principle used in the debian-installer package/project, the ISO building is by different software (https://git.devuan.org/devuan/installer-iso). The Devuan installer only offers the text mode process, and it does not include the gtk mode process.
The installation principle is to boot up a generic kernel+initrd (the installer) and then expand that by loading modules from the ISO appropriate for the target system while stepping through installation until there is a target filesystem set up. At that point, it runs debootstrap for a base system, transfers the so far captured setup details, and then starts installing packages via a chroot into the target system. It's the packages themselves that provide the second part dialogs through their postinst scripts.
I suppose this particular issue concerns the installer's kernel+initrd and how it interacts with the GPU.
]]>If you're booting legacy bios, you get an isolinux boot menu and you can press TAB to edit the boot command and add vga=<some vga mode that works>
Maybe check what the screen resolution is when you're running the desktop-live system and use that.
]]>I would suggest to switch HDMI with DP or vice versa, or try to use a different monitor if available.
]]>I found a 5year old thread of the same issue (i guess that devuan uses debian installer) :
https://forums.debian.net/viewtopic.php?t=132200
The image linked in that discussion is like what i see.
I tried the devuan_daedalus_5.0.preview_20230209_amd64_desktop-live image and it booted to gui with no problem. I write this line from using it.
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