2 Xboxes one house...possible?

Okay...my wife and daughter have started getting into Fortnight on the Xbox. I'm super stoked about it, however I want to play COD at the same time. If we get a second xbox, can we play our separate games at the same time without having to buy the games again? Using my games with gold and game pass Ultima? I tried searching and found some answers, but will admit I don't understand the home console thing or find a straight answer on if I can play COD and they play Fortnight on different xboxes at the same time. Thanks in advance ☺️