gokrazy is a very cool project and something I'd like to see more of. It's not a unikernel per se but it shares the idea of packaging your code and the OS together and shipping it as one. My dream would be a pure Go userspace library to do absolutely anything related to system management you'd need, like managing networking, connecting to Wi-Fi access points, performing upgrades and so on. But it's such a massive undertaking so we're stuck depending on software written in C via FFI or exec'ing shell commands -- pretty gross.
I run into this often and share the same desire. I quite like Go, but unfortunately the interaction of "my interests" (such as the userspace library you suggested) and "things Go excels at" isn't very large. Having to do everything important through FFI or shell commands defeats the purpose of writing Go, imo.
It's intentionally not designed to be a drop in replacement for Bash though. I saw no point replicating all of the problems with Bash when writing a new shell. So it does a lot of things different -- better in most cases -- but that does also create a learning curve too (I mean you're literally learning a new language).