A few years ago we bough our daughter a set of Snap Circuit https://www.google.com/search?q=snap+circuit&tbm=isch She liked it a lot (get one with a fan). I think it's a toy for a 7-10 year old, so not in the range of age you want :( , but consider it in a few year.

Later, we bough her an Arduino set, one with instruction for small projects. I can't find the exact set, but there are a few sets of $15 in https://www.amazon.com/s?k=arduino&i=electronics We added a few additional pieces, like a 7-segment led display. This can be suitable for the 15yo.