It seems likely that there is a bug in the ocaml world "docs do not explain how to just install the compiler from the native package manager without going off the rails and doing it on the side with ocaml tools". If that's true, that bug should be addressed to the ocaml.org world.
Unison should not cross into supporting ocaml, much as we do not explain how to build anything else necessary from source.
Instead, we should simply point to the ocaml world as a URL to go with "you must have an ocaml compiler".
A candidate URL is
https://ocaml.org/docs/up-and-running
It seems likely that there is a bug in the ocaml world "docs do not explain how to just install the compiler from the native package manager without going off the rails and doing it on the side with ocaml tools". If that's true, that bug should be addressed to the ocaml.org world.