Thank you for considering contributing to this project. It means that you not only find it useful, but that you think there's something that could be done to make it more useful, or useful to more people. Any suggestions are welcome, including open discussion about the direction of the project as a whole. Don't worry if you can't code, can't document, can't design graphics, can't translate or have trouble with english; I still want to hear from you.
That being said, the current vision is to be a stock Gnome project, although not necessarily pure Gnome. For example, there are no plans to include integration for file managers other that Nautilus, however contributions for other file managers would be accepted so long as including them doesn't force other users to install dependencies that they don't need or wouldn't normally be found in a stock Gnome desktop.
Additionally, all code should be written in GJS if at all possible and should not be written in compiled languages that are architecture dependent. As long as it can be unpacked from a ZIP and ready to go for everyone, that's good enough.
The best way to get in touch is either by opening a new issue or by contacting one of the current contributors directly.