If you would like to contribute to the docassemble project, the most impactful thing you can do is use the software. You are also encouraged to participate in the Slack group, contribute bug reports and feature requests, and attend Docacon.
If you would like to help fix bugs, pull requests on GitHub are welcome.
If you would like to contribute code for new features, the best practice is to first write your features as an add-on package and let the community know about it on Slack. If it makes sense to make the feature part of core docassemble, it can be moved into the core.
If you would like to contribute money, note that docassemble is not an entity and is not sponsored by any entity, so it is not possible to fund the development of docassemble directly. However, you are welcome to make a financial contribution to the Merlin Legal Open Source Foundation, which is a non-profit that supports the cause of free and open-source software in the legal field.