Yes, to read querystring values in the view, you can do this:

@inject Microsoft.AspNetCore.Http.IHttpContextAccessor HttpContextAccessor
@{
    var testValue = HttpContextAccessor.HttpContext.Request.Query["test"];
    <div>Value: @testValue</div>
}

As you say this is more of a "how it is in .NET Core" rather than Umbraco related - the main change really being that you need to inject the service responsible for accessing the HttpContext into the view.

Andy