> What do other languages' standard libraries do to walk around clone3 then?

They don't offer generic clone3 wrappers either AFAIK. All the code I've seen that uses it - and a lot of it is not in standard libraries but in e.g. container runtime implementations - has its own special-purpose code around a specific way to call it.

My point is not that other standard libraries do it better, but that clone3 as a syscall interface is highly versatile, moreso than it could be as a function in either C or most other languages. That is, the syscall API is the right layer for this feature to be.