I find it really interesting, that not only did they do the work of creating a JIT using the CoreCLR for CPython, they created a JIT API so that their system is augmenting CPython and not taking it over. Solid engineering.
This also means that one could implement an alternative JIT using Rust or OCaml.
[1]: https://github.com/microsoft/Pyjion#how-do-this-compare-to-