Thanks for taking interest in contributing!
If you think that the extension is missing some useful features which would benefit a lot of developers, you can open an issue describing your use case or discuss the ways of implementing such features if you want to do it yourself.
Firstly, read the Godot Engine's Contributing document as Goost shares similar ideas.
Secondly, read the Goost's documentation on general principles which governs the development of Goost, how they potentially differ from Godot development, and what kind of features are accepted.