Comment by jmnicolas

In case you don't know, GrapheneOS is based on the open sources parts of Android (AOSP) so the apps are developed on Android's JVM (Dalvik?). Maybe it's possible to code with Clojure.

Actually it looks like it's possible : https://github.com/clojure-android

Myself I'm learning Flutter to be able to develop my own apps when I can't find what I need on FDroid.