Andy has clarified that the unsigned vmlinuz in the .deb does include the stub. However, it seems I'm now unable to reproduce the original issue: if I block the i915 driver from loading on an installed system, leaving me with EFI VGA in /proc/fb, I get a perfectly usable console on boot. Need to investigate further to understand why this is reproducible with the server image but not with an installed desktop.
Andy has clarified that the unsigned vmlinuz in the .deb does include the stub. However, it seems I'm now unable to reproduce the original issue: if I block the i915 driver from loading on an installed system, leaving me with EFI VGA in /proc/fb, I get a perfectly usable console on boot. Need to investigate further to understand why this is reproducible with the server image but not with an installed desktop.