What to do with GPIO

Note, I’m not an EE so this question may be naive.

I’m thinking of things to do with GPIO, and it occurred to me that one may be able to use them with hybrid phasers/couplers in a butler network, or similar beam forming system.
I then imagined a guy named Nyquist, laughing at me while twisting his mustache.

Thoughts? What are others doing with GPIO?

What’s a Butler Network? Google brings me to the university.

Sorry, Butler Matrix