[cyphar]

There is a time namespace proposal[1], but currently the answer to this question is no. The reason is that timekeeping is incredibly complicated within the kernel (for instance -- when userspace gets the current time, it's read from a vDSO page that the kernel injects into every process and thus is updated by the kernel asynchronously). Adding different clock speeds is already non-trivial, let alone switching out different time backends.

The current time namespace proposal just allows you to set the current time separately from the host, which is actually quite a difficult thing to do already (it takes 20 patches)...

[1]: https://lore.kernel.org/lkml/alpine.DEB.2.21.1810022310360.1...