With all the integrated standard functions Mathematica is such an incredible tool. We really need an open source version of it. Even if we implement only 10% of the features it would be already incredible useful.
I started working on an implementation in Rust called Woxi (https://github.com/ad-si/Woxi) and I hope to find some contributors, as it is such a gargantuan task!
Here's a 10% clone of Mathematica - https://mathics.org/