I've been doing more experimenting. Also in the box of recycling that my wife had is her old Dell laptop, a more recent machine with i8xxx series processor. I changed boot order and disabled secure boot, it booted to Lubuntu very quickly. I poked around and Linux couldn't find the hard drive in the machine, maybe I had removed it previously. That machine also doesn't have a battery so it isn't a very good candidate to becoming a usable Linux computer without spending some money on it. That seems to indicate that the USB stick is working correctly.
Next I pulled out my old Toshiba laptop that I used for travel. It is about the same era as the Toshiba from my wife but is a different model with different dual core processor and different bios, same amount of RAM. It did the same behavior as the other Toshiba- try to load grub, black screen, try to load grub, black screen, etc.
The last bit of junk from the closet is my old Dell Latitude that I was using until 2 years ago. It has a pretty fast dual core processor for the era and 4GB of RAM. It boots to Windows 10. I rearranged its boot priority and it gets stuck in the same grub groundhog day repeating as the 2 Toshiba machines. I look through every entry in its extensive bios looking for things I might have read about. I disabled fast boot and now it must take 5 minutes to boot, but it's still stuck in the looping it just takes 5 minutes per loop cycle.
So far grub is batting 1 out of 4 on old hardware. I'm not going to try it on my 2 new computers or my old desktop.