If anyone's interested, I have an implementation of the C++ Standard Library for Arduino that includes the <random> header and has all the PRNG engines. You can get it here: GitHub - Michael-Brodsky/PG: Rapid application development tools for avr/samd/megaavr architectures (Arduino, STMicro, Teensy).. You'll need to install the whole library, starting with the root folder pg/ into your sketchbook/libraries folder (where all user libraries go). If you use the green Code button on Github to download a .zip file it'll probably name the root pg-main, but you can change that to just "pg". Hit me up if you need help. Cheers!