(See immersive-web/webxr-gamepads-module#2 for the "squeeze" naming if unfamiliar)

A couple of us discussed this a bit at TPAC: We think it would be useful to expose a set of squeeze events like we have select events, for a "primary squeeze" action (currently defined in the gamepads module). This basically exposes an event for buttons[1] (if nonempty) just as select is an event for buttons[0]. Devices would not be required to trigger this event (unlike the primary action, which is mandatory).

Select and squeeze seem to be the two main webxr-exposed buttons that are common across most devices and have familiar and uniform meanings (it wouldn't make as much sense to expose, say, a "B button pressed" event)

This is also good for AR devices that wish to expose hands as input sources: these hand-input-sources do not have gamepads, but can have select or squeeze events. We eventually need to come up with a way to expose articulated hand tracking, but a lot of applications need just one or both of these events to work, without needing gamepad support.

cc @thetuvix @NellWaliczek