> It’s C++ 20/23 without virtual memory

Not sure what you mean by this? Virtual memory is implied by the CPU MMU and consequently OS kernel. Perhaps you meant they use a lot of custom memory allocation schemes?

Otherwise, I agree that the bar is quite high since (1) the problem at hand is already too complex (scalable LSM), and (2) pretty much anything in the code is custom made, e.g. avoiding the OS kernel as much as possible. And they pay peanuts for the skills needed to do the job.