Important files to add a new sidebar button in nebula:
/src/views/sidebar/content.blade.php
/src/views/wrapper/script.blade.php
public/editor/edit/sidebar.php
client/wrapper.blade.php
Its really just copying the code of the alredy existing buttons and replacing all variable names
Did 5 buttons without ANY PHP knowledge in ~1h
So it's really not hard and stop writing to Emma about it.