Its worth mentioning that this seems to be purpose made to work with an entire custom rust OS Redox-OS. I didn't know that at first glance since I never heard of it. It also answered my question of whats wrong with NuShell?

Have they considered nushell though? It works on both POSIX-like OSes and Windows so it's not platform specific. I'd like to know if it wasn't ready in time (then why not work together instead of starting a new shell, pun not intended) or if there are some technical reasons.

I don't see a single mention of nushell in their readme or mdBook which is a shame.