Full stacked developer

I am looking for an experienced full-stacked developer for a project. The selected developer should be well-versed in JavaScript(using mongodb, flutter, to include some code on firebase, and some experience with web and web extensions), as it is a required language for this project. The project is intended to maintain an existing application, not to build a new one or to improve an existing one. The timeline and scope of the project will depend on the progress we make. As such, depending on the progress, we are open to considering bringing on board the selected developer for a long-term engagement.