(The below paragraph is incorrect, see next comment, left for posterity)
Sadly, no, even with the static support Crystal offers, it has certain gaps on Linux (glibc) and MacOS (system libraries). That said, I believe for the vast majority of use cases, a Crystal binary will “just work”.
Two decades in the Vim community has proven to me, over and over that plugins with no dependencies almost always win – even if functionally worse. I am not saying it is even a functional issue, or purely logical – it is emotional. Adding this with binaries or system requirements “feels bad” and people trend away from it.
I happen to have certain old Redhat machines I use Kakoune on (even had issues compiling Kakoune statically to work on them) – so staring down the barrel of another binary not provided by the distro that I have to make functional was a huge part of why I created the KPMS: Kakoune.com Plugin Maintainers Squad and moved connect.kak into it (with @alexherbo2 help and blessing).
Connect.kak is the single most important plugin, it works amazingly and stays out of my way – and works everywhere I need it to.