Looks like a couple of years back the Docker extension authors went down a similar path and it wasn't entirely smooth.

microsoft/vscode-docker#1908

@gjsjohnmurray , Looks like it did ultimately get merged, though, right? And in this case, I don't think there's any special editor involved (.env files seem to be treated as plain text files).

This is up to each file icon theme to implement. Our default theme is the seti icon theme so feel free to open the request there. It doesn't appear they have glob support though making this case hard. I've unconsciously started naming my files .dev.env instead of .env.dev to get around this. Here's the mapping file https://github.com/jesseweed/seti-ui/blob/master/styles/components/icons/mapping.less

Thank you. In case anyone wants to track this: jesseweed/seti-ui#652

In the end I don't think they can do that without listing every possible .env we have this feature request actually which isn't easily implementable #12493

That issue is an interesting read. Perhaps just a list of the most common .env.* examples would be at least better than the status quo of only .env.