B11 and G10 - what to get £40 ish

[SongASing]

I need to get a present for about £40 each (maybe pushing £50) for a boy aged 11 and a girl aged 10 that I don't know very well and I haven't seen all year so have no idea what they're into. I have got them onesies and radio/speaker before but run out of ideas this year. Their parent has no suggestions!
Any ideas??

Do they have a console.. game?
Converse
Trainers
Elmers slime kit

No idea whether they have a console, trainers seem too personal. I am so stuck! Will check out slime, thanks.

Even a smyths or John Lewis voucher?

My DD9 loves choosing something.

For that amount of money, if you're not sure and the parents aren't helping, I'd go for a voucher and a small token gift. Feels like too much to take a punt, especially for kids that age who might be starting to get fussy.

Books if they read - Harry Potter, David Walliams, Series of Unfortunate Events. Find out if they have devices - apple/Google play giftcards or Roblox. Board games or card games e.g. exploding kittens.

Vouchers and a small gift. They can have very specific tastes as that age.
Maybe the Lego Dots photoframes for the girl?