Just out of curiosity and to see if it is possible I wrote a small app for Android that can connect to a painlessMesh network (https://gitlab.com/painlessMesh/painlessMesh) and act like a node.
So far the app can connect, request routing info (NODE_SYNC_REQUEST) and send single (SINGLE) and broadcast (BROADCAST) messages.

Restrictions:
- Not supported are (TIME_DELAY), (TIME_SYNC) and (NODE_SYNC_REPLY).
- The app is connecting to the closest painlessMesh AP. Due to restrictions of Android it can not have AP and STA mode running in parallel.

The source code is available as well on Gitlab ==> https://gitlab.com/beegee1962/painlessmesh_android.
Website for the project: https://desire.giesecke.tk/index.php/2019/04/09/painlessmesh-and-android/

- The app is 100% open source and has no ads.
- The app asks for the user permission to access location because since Android > V6 requires permission from the user for location service to scan WiFi networks. Makes no sense, but that's how it is :(