I did verify with lsblk, with a listing before and after plugging in the stick to be absolutely sure.
I also did verify the checksum of the ISO.
I'll double check SecureBoot, but as I mentioned, the same ISO written to the same stick with Fedora writer did boot in the same machine it wouldn't boot from with the dd version.
I know it's something I did or didn't do to make it work correctly, so this is not me trying to dunk on dd, just trying to understand what I did wrong.