The noise coming from an open microphone has enough entropy for what we’d usually assume to be random.
It is possible to hit a bottleneck getting random numbers, but there’s /dev/urandom which shouldn’t block it’ll just keep outputting without enough entropy to guarantee pseudorandomness.
Usually you’ll know if you’re hitting one of those bottlenecks, probably it’ll only come up in production or hopefully in load testing.
Kkklanada