I think that any microprocessor which purports to be able to internally-generate "random numbers" should also be equipped with an input (possibly a single line) which is intended to be connected to an external source of random numbers, intended to be mixed with the internal random source, for example:

http://www.fdk.com/cyber-e/pi_ic_rpg100.html    

   or  

https://www.idquantique.com/random-number-generation/products/quantis-qrng-chip/?gclid=CjwKCAjwxt_tBRAXEiwAENY8hU5d5R0aujGaQjDCHS6Ej_gwwLk8Sz9Z6XG71zec2o9HlcTyjHPaIhoC7HMQAvD_BwE

   or

https://ieeexplore.ieee.org/document/847868

This should minimize the possibility that defects in one source can affect the randomness of the ultimately-used data stream,