Really happy to hear this 
Help is always greatly appreciated, so big thanks for asking about it!
It depends on the kind of stuff you want to work on and how much time you are able/willing to invest in learning about the internals. A significant part of the API surface is still undocumented and not all preliminary comments/docs that have been written so far have necessarily stayed accurate throughout the refactors.
With that said, there is a significant amount of polishing work to do in several areas which have kind of stabilized now. Also, it probably wouldn’t hurt to get some early feedback from the community on how it is to work with the new version in the first place. This would help us improve on aspects that matter for plugin developers.
By all means feel free to go ahead and open/comment if you see any issue you’d be interested in picking up. We can take it from there