Hi @Jameracho and welcome,
You can easily synchronize your local codebase with your Playcanvas editor with the following tool:
It’s quite handy for use with NPM, webpack/rollup, Typescript etc.
Your other idea to use the editor as a scene exporter can work too. You can use the Playcanvas rest API to easily export/download a build to use with your importer. In my experience this is a good compo, but the Playcanvas editor is powerful as well so I’d advice to not easily get away from it.
There isn’t an official API for plugin support in editor right now, though there is already an unofficial editor API and a solution that can help you write plugins today: