These are AOSP apps for the most part. They are maintained despite not looking/being very modern.
There are ongoing efforts to replace/improve them, such as the GrapheneOS Camera (alraedy in production) which replaced the old & broken AOSP Camera app. It has a built-in gallery which may lay the foundations for a full-fledged GrapheneOS Gallery app in the future. A community member is also trying to give it a try.
FlorisBoard has been considered to replace the AOSP keyboard but it needs improvements, some of which have been made by GrapheneOS contributors. It's still not quite ready.
Of course, contributions are welcome but I think the project is mostly interested in fixes rather than large commits that are difficult to maintain in the long term, so keep that in mind.