The installation is actually complete (not that it was easy), but this still seems like the correct category to ask for the help I need.
First off, the output of sudo update-grub:
Sourcing file `/etc/default/grub' Sourcing file `/etc/default/grub.d/init-select.cfg' Generating grub configuration file ... Found theme: /usr/share/grub/themes/zorin/theme.txt Found linux image: /boot/vmlinuz-6.5.0-35-generic Found initrd image: /boot/initrd.img-6.5.0-35-generic Found linux image: /boot/vmlinuz-6.5.0-27-generic Found initrd image: /boot/initrd.img-6.5.0-27-generic Memtest86+ needs a 16-bit boot, that is not available on EFI, exiting Warning: os-prober will not be executed to detect other bootable partitions. Systems on them will not be added to the GRUB boot configuration. Check GRUB_DISABLE_OS_PROBER documentation entry. Adding boot menu entry for UEFI Firmware Settings ... done
So I guess if anyone can tell me how to "Check GRUB_DISABLE_OS_PROBER documentation entry." that would be a good start. I don't know the command for that.
grub isn't the only thing struggling though. I'm quickly approaching the conclusion that I need to flash my UEFI. currently my computer will auto-boot into Zorin. if I interrupt that with F11, the boot menu looks like this:
Although that entry has no text, clicking on it or hitting enter will successfully boot into Zorin.
On the other hand, if I go into the full UEFI settings, it is perfectly capable of detecting both the Zorin and Windows bootloaders (as well as a bootable USB if there is one)
thing is I don't see how the UEFI could have gotten corrupted like this - even though it worked just fine up until my Manjaro upgrade blunder. if it is a corruption, it seems pretty minor, and I could live with it so long as grub bootloader was working, and this didn't put me at risk of worse problems down the line.
