re peripherals, the minicommand has a randomizer as part of the monster firmware, but personally i find it’s more useful for screwing around and exploring individual sounds than introducing global randomness into a pattern. there might be other firmwares i haven’t tried that do more, but for your goals i wouldn’t buy a mc just based on that one alone.

more generally: have you tried aiming free-running lfos at lots of parameters, including other free-running lfos? i find that’s a great and easily accessible source of wild evolving effects.