We already offer basic support for aggregation and indexing, and we are adding as many features as we can, see our roadmap [1].
We are mainly building on our user's experience with running FerretDB and add features to our roadmap accordingly. We are not aiming to implement the entire feature set of MongoDB, of course, but the majority of MongoDB workloads are not utilizing the full feature set, either.
That being said, we do have some automation in place. The public part is there: https://github.com/FerretDB/github-actions We are planning to do more there, open source the other part, and then blog about it.