hm. well assuming they have no network and don't otherwise encrypt bits that an attacker could get ahold of, it's probably fine.
the bigger issue would be something like spawning a bunch of servers that share the same rng state that can then be manipulated by an attacker (and therefore encrypt different data with the same key+nonce and such).
https://github.com/firecracker-microvm/firecracker/blob/main...
The VMs launch super quick in < 1s they are actually running a job.