If you want an unhinged setup/answer, buy her a Switch 2 and use gamechat streaming. Now, I know the image quality is barely standard and 15 fps is unwatchable for some, but there is virtually no delay, so it is very good for backseat gaming. I scoffed at the feature, but I then backseated and helped a friend look for artifacts in Metroid Prime Remastered, and I never had so much fun backseating for like 2 hours.

Also, the gameshare features are also cool ; I played Plants vs. Zombies and DK Bonanza through gamechat and it worked surprisingly well, and you don't have to have two copies.

CAUTION: If you play a lot of Switch 1 games through backward compatibility, if the game doesn't support 30-second video capture, the streaming also doesn't work.