Ok, so, sort of NSFW links ahead, but there's actually an open source project that does this.
The Nogasm is a pleasure denial project that uses pelvic floor contraction frequency, as sensed by pressure output in an air filled cavity, to prolong play.
Output from either of these devices could be used for that, though discerning between voluntary versus involuntary muscle contraction would be challenging.
Seems like it would be pretty easy. Send a "dot" for three contractions each one second apart. Send a "dash" for three contractions each three seconds apart. It would be pretty slow, but it doesn't need to be fast.
It can't be too slow, if it takes too long to input moves, you can't input in realtime, or you have to slow down your play and that can look suspicious.
The Nogasm is a pleasure denial project that uses pelvic floor contraction frequency, as sensed by pressure output in an air filled cavity, to prolong play.
https://github.com/nogasm/nogasm
There's even a upscale ESP32 based version of it called the Edge-O-Matic, complete with its own Flappy Bird implementation.
https://maustec.io/pages/edge-o-matic
Output from either of these devices could be used for that, though discerning between voluntary versus involuntary muscle contraction would be challenging.