What they did today doesn't sound too bad to me.
My dd is 13 yrs: she and her friends make mini music videos, play on the Wii (just dance), sit and chat/paint nails/plait hair elaborately, last time they made a murder-mystery video
and potted up hyacinth bulbs for Christmas, and they also do foodie/art projects. Art activities have included, among other things, lying on the lawn and painting pictures (in oils) of their feet
and complex origami lamp shades and, weirdly, (but they suggested and enjoyed it) flower arranging. They also make endless friendship bracelets. And they are still in to making elaborate tent/den-like structures with duvets and blankets etc, even at their age and squishing in to it!!
I often have cakes\cupcakes that just happen to need decorating when they are around
and they have made three course meals entirely on their own (with much shrieking involved) last time it was: cheese balls nibbles, pasta bake followed by daschund shaped biscuits!! They've also made fresh pasta and pizzas from scratch.
They also like doing activities with animals: dog training, rabbit brushing, rabbit enclosure cleaning (never asked them to do the latter I hasten to add, they volunteered.)
Although you don't want to be actively involved at this age, I agree it's helpful to "just happen to have the wherewithal to do certain activities lying around" sometimes. I've found they particularly like activities that are seemingly adult where they have to "step in" ie "I am just preparing these cakes for so and so, but I am running out of time and have to call Great Aunt X, can you take over pls?" Or, I am painting this wall but have to break off now, can you finish it? Gets them away from the screens for 30 mins or so anyway!