Your numpad solution looks great! Would you have a photo of the whole setup? I thought about doing the same, but I fear to end with cables and PCB everywhere in my children's room if I take this path :)
The pi and power are hidden behind a bookshelf, so all that is actually visible is the numkey and the speaker.
[0] https://www.microcenter.com/product/608178/4_Official_Case_-...