Signals and Threads had an interview with Anil Madhavapeddy last year:

https://signalsandthreads.com/what-is-an-operating-system/

He talked about the work to put a multicore-ready memory model[1] and GC[2] under OCaml.

[1] https://anil.recoil.org/papers/2018-pldi-memorymodel.pdf

[2] https://arxiv.org/abs/2004.11663