[Feature Request] custom syntax highlighting

[mithom]

At the company i work at, we use a custom language nested inside of strings/comments of the main programming language.
In VSCode and many other editors i can add custom TextMate syntax highlighting, which greatly improves readability of our code.

I know this is a far stretch, but would it be possible for me to locally add custom code highlighting through the TextMate format?
Support for custom language would already be great, supporting injection grammars would be awesome.

This month i do not have time, but if you are willing to consider this feature, i can take a look at it myself in march.

If you need any more details, let me know!