Welcome to the keyboard building community!
It's never too late to dive into a new hobby...
That ortholinear 40% from Microcenter sounds like a fantastic start.
I love the compacts myself, using a HHKB Layout most of the time.
I bet your wife's question is one many of us have heard before...
My answer would be "What do you need another pair of shoes for?"
Anyway, great to have you here!