MB-N10 Battery Grip for Nikon Z5 Z6 Z7 Camera Grip - AliExpress
キングマ-MB-N10バッテリー用縦型バッテリーグリップホルダー,Nikon z6 ii z7 ii z6 z7 z5,カメラハンドル,1または2ユニットで動作,EN-EL15 - AliExpress
Got a couple Japan-only goodies for the Z6: A Z-GR1 extension grip and a neat green neck strap! I'm posting a review of the grip in the comments. : r/Nikon