Beyond the syntax looking a bit similar, Crystal is a very different language. Porting over a production application such as Shopify isn't something you do in an evening.
Just like in C, you have trivial, nontrivial, complex apps, then there's still a long way before production OS kernels at the extreme.
Many advanced libraries don't use metaprogramming much, and even if they do, it can be often made either more explicit or shifted to compile time.
Edit: The downvotes are interesting since the portability claim comes from my experience doing just that.