I thought that was already supported?
See GitHub Codespaces 
Jupyter Notebooks and maybe even better information at Jupyter notebooks on Codespaces
You should be able to use those approaches in some sort of console or command line access and then use jupyter nbconvert or jupytext to achieve “instead of running them on Jupyter notebook environment”, if that is your goal.
However, this is an premium offering from GitHub that costs real money and therefore you should be asking them for assistance and guidance.
Please read Getting good answers to your questions throughly and follow when considering posting here. No where in your first post was it clear you were speaking about GitHub Codespaces. And then in the screenshot you provide is simply the preview of a static notebook.
The last link there links to here that emphasizes ’ Search, and research’. Please read that and follow it.