The new joystick API coming in minisphere 4.2 will allow you to easily query connected input devices using Link, like this:
const link = require('link');
// historically, Sphere requires a gamepad with at least 2 axes (X/Y) and
// 5 buttons (A, B, X, Y, Start) for full operation.
var devices = link(Joystick.getDevices())
.where(function(it) { return it.numAxes >= 2; })
.where(function(it) { return it.numButtons >= 5; })
.toArray();
This allows minisphere to support any number of gamepads while at the same time allowing games to ignore any devices without enough inputs. While that latter thing was technically possible in Sphere 1.x, the engine itself would only tell you about 4 devices max.
Not that I can see too many people hooking up 10 gamepads to their computer, but the API flexibility is there to allow it if they do.