Would it be able to abstract out the language specifics and treat code folding similar to how emmet handles it...
i.e.

    "emmet.includeLanguages": {
        "php": "html",
        "blade": "html",
        "javascript": "javascriptreact"
    },

So for code folding it could be...

    "codeFolding.IncludeLanguages": {
        "php": {
            "openTag": "//#region",
            "closeTage": "//#endregion"
        },
        ...etc...
    }

This is just an off the cuff idea for implementing this and I'm not sure that it's possible, but the goal would be to not be dependent on the language plugin developers to implement the feature.