Not only these, but I also recently noticed OCaml-written parts of Moby[1]. Another significant example is Tezos[2]. So far, OCaml became much more modern and usable in the last couple of years. The biggest missing parts are multicore[3] and solving the metaprogramming issues[4]. Both are being worked on, and, hopefully, will be ready in a couple years.

[1] https://github.com/moby?utf8=%E2%9C%93&q=&type=&language=oca...

[2] https://tezos.com/

[3] https://discuss.ocaml.org/t/multicore-ocaml-january-2020-upd...

[4] https://discuss.ocaml.org/t/the-future-of-ppx/3766