I'd wager that a complete 8-bit system with printer and cassette storage is a better tool for learning.
I'm betting the boundless possibilities presented by direct I/O control of a servo would do more to equip a kid for life than the range of choices presented in an app.
Making your ideas manifest is fascinating, regardless of whether they're tangible.
Personally, I want my kid to be on the TX pair, not the RX.