Unikraft is good if you want to run untrusted code, giving a way for developers to extend functionality on your platform in Python (or JavaScript if you use Ducktape, also in their examples) - kind of like AWS Lambda and the likes. Besides the added security from running in a virtual machine, unikernels boot extremely fast. Without applying any optimizations, I have a QuickJS unikernel that boots, runs JavaScript and shuts down within 400ms (running in Windows -> VMWare -> Linux -> KVM+QEMU). This performance would be hard to get with Docker and a Linux distro.
For more details, check out the library for details: https://github.com/unikraft/lib-python3
Think of it as if Node.js could be directly installed on a PC and no Linux is needed.