How to list files from directory with wildcard in a Gnome Shell Extension?

I have managed to read the content of a file from the disk with this snippet:

const { Gio } = imports.gi;   

class Indicator extends PanelMenu.Button {                                                                                                                     
 
   _init() {                                                                                                                                                  
        const file = Gio.File.new_for_uri(                                                                                                                     
             'file:.config/wireguard/current_vpn');
        const [, contents, etag] = this._file.load_contents(null);
        const decoder = new TextDecoder('utf-8');
        const contentsString = decoder.decode(contents);
    }
}

Now I am tryning to list all the *.conf files from a directory. But I cannot find a proper way to do that reading the Gio docs

You'll have to enumerate the files in the directory and perform your comparison on the file names as you go. There are examples of enumerating files in the File Operations guide on gjs.guide:

const {GLib, Gio} = imports.gi;

const directory = Gio.File.new_for_path('.');

const iter = await new Promise((resolve, reject) => {
    directory.enumerate_children_async(
        'standard::*',
        Gio.FileQueryInfoFlags.NOFOLLOW_SYMLINKS,
        GLib.PRIORITY_DEFAULT,
        cancellable,
        (file_, result) => {
            try {
                resolve(directory.enumerate_children_finish(result));
            } catch (e) {
                reject(e);
            }
        }
    );
});

while (true) {
    const infos = await new Promise((resolve, reject) => {
        iter.next_files_async(
            10, // max results
            GLib.PRIORITY_DEFAULT,
            null,
            (iter_, res) => {
                try {
                    resolve(iter.next_files_finish(res));
                } catch (e) {
                    reject(e);
                }
            }
        );
    });

    if (infos.length === 0)
        break;
        
    for (const info of infos)
        log(info.get_name());
}