What I want to know is this: What is different about the bootloader such that FreeBSD won't even get to the boot options screen (just blackness) whilst GhostBSD installs perfectly? This is neither gripe nor complaint nor criticism. I just wonder why I can press "1" for normal boot (to install the OS) on GhostBSD, but can't even get that far with FreeBSD (or Linux). I REALLY REALLY REALLY do not want to create controversy. I am just wondering what could be different about the bootloader on a USB stick. FYI: Hardware is an ancient iMac that I'm trying to restore. No Linux OS or other BSD works. Only GhostBSD or El Capitan.

I am just asking. Don't get all up in arms. I just want to know why or how the bootloader might be different. Other than GhostBSD (or El Capitan) zero OS installers give me anything other than a black screen. I wonder why.

I am surprised that the boot loader works. The only difference is that I use FreeBSD 13 stable instead of FreeBSD 13 releases. Maybe there is a fix in the stable branch.