Worth calling out that the syntax highlighting support is used to highlight several languages in github.com. (Linguist is still used for the long tail of languages, but we plan to migrate more and more over to tree-sitter-based highlighting over time.)

The query language is also what's used to drive the fuzzy/ctags-like Code Navigation feature. Both of those are powered by tree-sitter query files defined in each language's repo, like these for Go: https://github.com/tree-sitter/tree-sitter-go/tree/master/qu...