Like the others say it depends a lot on what she's interested in. Have a think and look for suitable christmas presents maybe? e.g. mine had a lot of fun with electronics kits, or there are a huge range of kids science kits. Again, if science is her thing also look out the dyson challenge cards - lots of simple practical experiments using stuff you might already have around the house.
Or if she's a reader, explore authors she might like. Classics are quite good for younger kids as there's nothing age inappropriate but great vocabulary and the challenging of understanding the different time and culture they're written in. There are some lovely non-fiction books for primary school kids too. Even some of the older-targeted usborne lift the flap type books have some heavy duty ideas and information in them. We had a maths one and a human body one that got heavily used. The horrible history/murderous maths etc series are a lot of fun but also a lot of information.
Writers like nice (lockable?) notebooks and pens, story dice are quite fun as an idea but DD never took to them. Really just time and notebooks and scrap paper and random projects and bits of writing got strewn around the house. She does it less now, but I still occasionally find random poetic scribblings from primary school days, often on the subject of how annoying her brother is but the vocabulary is great 😂
Languages - mine liked playing around with duolingo, I know you said no screens but it's only a few minutes a day.
Anyway, give us a clue what her interests are and perhaps we can give you some more targeted ideas.
I know it's frustrating when school aren't even trying. I do think it's better to have a 'special interest' outside school than to just try to push ahead and do more advanced maths or science for the sake of it. (Unless maths or science are the special interest). More advanced writing doesn't really require any more input than standard writing, school give them the prompts they can write as beautifully as they are able. And reading you just need to find recommendations and try stuff to see what she likes.