How do you receive a text file Shared from WhatsApp

Question

I'm trying to read a text file from WhatsApp and can find the filename in the intent, but not the file itself.

Also confused as to what the MIME type should be. Should "text/plain" be used for both shared text AND a shared text file? How does one differentiate between one and the other?

[IntentFilter(new[] { Intent.ActionSend },
    Categories = new[] { Intent.CategoryDefault },
    DataMimeType = @"text/plain", Icon = "@drawable/icon")]

void HandleSendIntent(Intent intent)
{
    //extra1 = "myfile.txt"
    var extra1 = intent?.GetStringExtra(Intent.ExtraText)?.Trim(); 

    //extra2 = null
    var extra2 = intent?.GetStringExtra(Intent.ExtraProcessText)?.Trim();

    //uri = {content://com.whatsapp.provider.media/item/83019679-d3d1-4e43-805e-7a05734e88df}
    Android.Net.Uri uri = (Android.Net.Uri)intent.GetParcelableExtra(Intent.ExtraStream);
    
    string doc_id = "";
    using (var c1 = ContentResolver.Query(uri, null, null, null, null))
    {
        c1.MoveToFirst();
        string document_id = c1.GetString(0);

        //doc_id = "myfile.txt":
        doc_id = document_id.Substring(document_id.LastIndexOf(":") + 1);
    }

    //a = null
    var a = Intent.GetParcelableArrayExtra("com.whatsapp");

    //b = null
    var b = Intent.GetByteArrayExtra("com.whatsapp");

    //c = "text/plain"
    var c = Intent.Type;

    //
    //Where is the file????
    //

}