My boyfriend’s second oldest niece is slightly younger than your niece (she turns 11 in a few months). She’s crafty and was very excited when she was gifted a tie dye kit to make her own tie-dye t-shirts. Boyfriend’s SIL was less-than-thrilled because it was messy, I guess (have never tie-dyed a thing so I don’t know how much annoyance you need to factor in for your sister). She also likes board games, so we got her Clue for Christmas and she loved it.
I think around that age, anything that makes you feel kinda cool, like you’re coming into your own as a teen, is a good idea. What that is for kids these days, I’m not sure.