For games you might would enjoy together on the switch there is MarioKart and Arms, those are my wifes favorites, also Kirby and Donkey Kong are coming soon and they are great Co-Op side scrolling games
Cheaper on xbox but is on switch too, get Rayman Legends. Its a platformer somewhat like old mario games and can be played one or two players on the same screen. Also on both systems, Sonic Mania is just like old Sonic Hedgehog, can be played 2 players locally as well but is a little harder than mario and rayman in my opinion.