To add some more information here:
I'm not getting to the Unraid boot option GUI referenced in step 2 here: https://docs.unraid.net/unraid-os/manual/troubleshooting/
I've tried 3 different drives - a random USB 2 drive I had lying around, the Patriot 32GB, and a 16GB SanDisk Ultrafit. First and last by doing the manual install process, and the Patriot both manually and via the USB Creator tool.
Searching the forums for similar issues it seems like mostly it's "I forgot to rename 'EFI-' to 'EFI'", but I have definitely confirmed that the folder is appropriately named; each drive shows up in BIOS as a UEFI boot option, and I verified that it was first in the boot order.
I'm pretty sure I'm following the suggested settings here: https://docs.unraid.net/unraid-os/getting-started/advanced-bios-config/
Specifically, it is definitely the primary boot device, storage controller is not RAID, virtualization and IOMMU are enabled, and it's a direct USB port off the motherboard, and fast boot is off.
For all cases, I get to the BIOS splash screen but it hangs prior to seeing any Unraid OS elements.