Your previous suggestion to use a Ngnix as a reverse proxy of course works, but it is inconvenient for development.
In my development environment dfx runs in a bare-bone Linux container without a display server. The browser would run in another Linux container or on another physical machine. The physical machine and the host are in a different subnet, the containers share the same subnet but have different IP addresses, so accessing the dfx port via localhost does not work.
Don’t we use webpack for bundling assets which in turn comes with a devServer supporting HTTPS; dfx could be sensitive to such configuration? Besides, given that HTTP is discouraged, dfx should also support HTTPS in production mode.