Screen too narrow (82 + 7 > 87) for menu "Available disks"That is bad - we must make sure installation works on a 80x24 console. Can you send me dmesg output for all disks on that system? Sysinst needs to shorten names reasonably if they don't fit.
I removed disks until I was just left with the installer USB (from NetBSD-9.99.97-amd64-install.img.gz), but it still happened. Here's the full dmesg, with the SSD connected:
https://www.klos.com/~john/install_dmesg.txt
In your case I guess it is the boot method (UEEFI vs. BIOS) that makes the difference, as for UEFI you would have to select serial console in the UEFI setup, while for BIOS we can do it in the bootloader.
Is that what it is? So instead of special bootblocks, UEFI just uses "consdev com0" in boot.cfg? That would be so much easier.
Thanks! John