So, it's well known that the government planes operated for the US President are called Air Force One; less well-known is that this is a call sign given to any Air Force aircraft that carry the president, and that if the President rides in an aircraft owned by another branch of the US Armed Forces, they would become known as Marines One, Navy One, or Army One, while any civil aircraft that carries the US President becomes Executive One.
What about aircraft that are exceptions to the normal FAA rules for aircraft licensing, however? If the US President was riding in (or piloting) a glider, ultralight, or autonomous drone taxi, what would their call signs be, if any?