I would like to install Endless OS to a thumb drive.as if it were a hard drive. I have done this on numerous other distros so that kids can take their system with them to other computers. Is this possible with Endless.
Sure, just write the Endless OS image file to the USB disk. On Linux: https://support.endlessm.com/hc/en-us/articles/210654503-How-do-I-create-an-Endless-USB-stick-from-Linux-
From Windows, you can use a tool like Rufus to do the same; or you can Ctrl+click on the “advanced options” link on the first page. This should give you two options (Live or Reformatter) and you can choose Live. (The default live mode creates a USB stick that can be used to try or install Endless OS, but changes you make – like installing apps – are lost on reboot.)