Thank you so much! A similar add-on for Godot that can import Pixelorama files already exists, you can find it here: https://github.com/Technohacker/godot_pixelorama_importer
Pixelorama already has a page on Godot's showcase https://godotengine.org/showcase/pixelorama and is mentioned in the Awesome Godot list https://github.com/godotengine/awesome-godot 😁