Thanks everyone. It's for her birthday.
For Christmas, she is getting a cello, music books, pjs, vegan marshmallows and a boardgame (all of those are a tradition), a pack of body spray and a specific pre-order book. With the price if a cello, that is pretty much it. So nothing we can transfer to her birthday.
@Isyesterdaytomorrowtoday I agree, that gifts should be about the recipient but she'll just put money into her bank account so it's not much of a present. She also gets money from relatives. Harry potter is a no because (surprise!) not everyone likes it. We won't have an Alexa in the house. Fidget toys are a no because they won't be played with for longer than 5 mins. If she was that bothered, she'd use her pocket money. Plus everyone goes on about the environment and than buys stuff like that.
I might make her a voucher for a fancy drink and cake that she can claim that when she sees something she fancies so thanks for that.
The writing prompt books seem like an idea. I will check those out.
I will look into electronics kits. They seem like something she's enjoy. She's pretty clumsy so a soldering kit would need constant supervision which I don't think she'd like.
A necklace might also be nice. I think she'd like some sort of crystal pendant.
A neom pod thing might be a possibility too.
Some good idea. Thanks!