环境：Net6

string dirPath = "C:\\Users\\15298\\Pictures";
var fileProvider = new PhysicalFileProvider(dirPath);
app.UseStaticFiles(new StaticFileOptions
{
    FileProvider = fileProvider,
    RequestPath = new PathString(("/files"))
});
// 开启目录浏览功能  当访问 files 的时候 会把 {{ dirPath }} 目录列出来
app.UseDirectoryBrowser(new DirectoryBrowserOptions()
{
    // 文件提供程序
    FileProvider = fileProvider,
    /// 指定请求地址
    RequestPath = new PathString("/files")
});

完整 Program.cs

public static void Main(string[] args)
{
    var builder = WebApplication.CreateBuilder(args);

    // Add services to the container.

    builder.Services.AddControllers();
    // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
    builder.Services.AddEndpointsApiExplorer();
    builder.Services.AddSwaggerGen();

    var app = builder.Build();

    // Configure the HTTP request pipeline.
    if (app.Environment.IsDevelopment())
    {
        app.UseSwagger();
        app.UseSwaggerUI();
    }

    string dirPath = "C:\\Users\\15298\\Pictures";
    var fileProvider = new PhysicalFileProvider(dirPath);
    app.UseStaticFiles(new StaticFileOptions
    {
        FileProvider = fileProvider,
        RequestPath = new PathString(("/files"))
    });
    // 开启目录浏览功能  当访问 files 的时候 会把 {{ dirPath }} 目录列出来
    app.UseDirectoryBrowser(new DirectoryBrowserOptions()
    {
        // 文件提供程序
        FileProvider = fileProvider,
        /// 指定请求地址
        RequestPath = new PathString("/files")
    });

    app.UseAuthorization();


    app.MapControllers();

    app.Run();
}

http://IP:Port/files  访问目录浏览