It sounds like you're failing as a parent and blaming the Switch Lite instead. Before giving to her you should have a conversation and established rules. Furthermore, Nintendo has since day-one Parent Controls as an app. An electronic device, even more a gaming-focused one will make kids overblown their attention and make their spend less and less time with "analogic" toys. You making the one-sided decision of returning the Switch will make more harm than good and even make her sad(And probably be a little rebellious against you).