However, I've never believed it to be possible to have a language both as a shell language and a proper programming language for large-scale projects. I believe the two usecases are fundamentally antithetical, but I'd be happy to be proven wrong.
I'd say Powershell proves you right. Powershell has a great design, it has optional typing and access to a cornucopia of libraries via .NET.
Even so, they had to make some compromises because of the shell parts (functions return output, for example) which makes is quite finicky as a "proper" programming language.
On the shell side, the very nice nomenclature which makes it very readable and discoverable makes is annoying sometimes to use as a shell. That and the somewhat unwieldy launch of non-Powershell commands.
Someone who attempts to bridge the two has a ton of work to do, both in the research and in the implementation department. I guess Oil Shell (https://www.oilshell.org/) is the most realistic approach we have today. And it's probably still 1-2 years away from release and many more years from mass adoption (if that ever happens).
Edit: a-ok, probably elegance is meant in the same sense that C is elegant by cramming everything in a single statement using pre-/post-increment operators and assignments-as-expressions