As far as I know GitHub readme(s) doesn't support inline math equation or any latex/katex is not supported. I have found a site https://alexanderrodin.com/github-latex-markdown/ which convert latex code to image and this can be shown on readme files as image.
Inline math equation is sometimes badly needed and if this feature is enabled then may be it will be helpful for others.
Again sometimes we need to highlight some text with different color suppose,
This is a colored text , here "This is a colored text" should be in color red. And this feature is supported in document editor like "Typora" but when the file is uploaded to github then raw code is shown instead of colored text. I also know that GitHub's discards any HTML(most of the) but adding this support will be cool.