See, in situations like this it bothers me. People think that material things will express how they love someone, but the reality is that it’s just things you can simply replace.
Instead of buying them things like that, try to take them on trips and create meaningful memories with them. That’s how I see how someone who struggles with expressing emotions should show it to someone other than buy them a lot of things.
If you’re not careful, they might expect you to buy them everything they want and that’s all they will see you for. The occasional present or gift is always great but don’t make it a habit.
But then again, Everyone has their own ways of expressing their feelings. So do whatever makes you feel better.