SharpLang is an interesting project, and it's MIT licensed! I'm a little concerned that its stated goals are not as interested in standards implementation or multi-language interop (although it mentions emulating some features), however it is showing a lot of promise. I hope Microsoft continues to support the project officially and contribute back to it, as it could help speed up the adoption of .net on platforms where LLVM support is there first or is the most mature. Also, being MIT licensed, if successful it could enable more cross platform .net development from the open source/hobbyist/maker crowd. It might even replace some of the use cases for the .net microframework, maybe?
I didn't see pull requests from Santiago on github though. Is his work being done in a private repo?