Here's a quick copy/paste snippet you can use to create a reverse proxy server in Cloudflare. GitHub has a set of pre-installed packages with the default containers it provides. Learn how you can override the default PHP version. Here's my review of Netlify Dev after a few hours of using it.
Using the Heroku CLI you can copy all of the config variables out of a project into a local file: You can also do the opposite, push config values into a Heroku project: Hopefully you found this article useful!