Moska: Is a Ring Oscillator something that can be tested on the prospective customer's own (portable?) equipment? In other words, in a way that will remove all doubt that the performance witnessed is not rigged?

Yes, because the ring oscillator will oscillate with a certain frequency depending on the number of inverters it consists of and the time an inverter needs to change state (time-delay).

Let me quote Wikipedia again:

• If 'T' represents the time-delay for a single Inverter and 'N' represents the number of Inverters in the Inverter chain, then the frequency of oscillation is given by F = 1/(2*N*T).

The frequency F can be measured, the number of inverters N can be counted, so you can calculate the time-delay T, which is what we ultimately want to know. However, the potential customers must be able to count the inverters, e.g. by putting the ring oscillator under an electron microscope.