the --template currently only accepts local files. I would like to discuss implementing:
--in-tree-template index.html
Where the command
rclone serve http myremote: --in-tree-template mytemplate.html
searches for myremote:mytemplate.html and renders it. If not found, it renders the default template.
In subfolder myfolder, rclone will get myremote:myfolder/mytemplate.html and so on