If you like you can transform your filetype config to the Geany wiki, so more users can find and use it. E.g. create a new page under https://wiki.geany.org/config/start.
For the Scintilla lexer for syntax highlighting, you could add a feature request to the Scintilla/Lexilla project, maybe someone is willing to write a Pug lexer. https://github.com/ScintillaOrg/lexilla/issues
I'm closing this as it is unlikely that we will include the config into Geany directly.