Currently, there is only one way to edit code for Power Apps portals which is using the Dynamics solution and the somewhat limited online editor. This extension provides a local source control of portal code including web files like images or style sheets, web templates and content snippets. Once configured, the extension loads all portal code and files to a local project folder. Then, you can edit, create or delete files. These changes can be pushed to the portal using the source control pane within visual studio code.
This seems like a worthwhile project but It didn't work for me. Is this project still under development?