Most pilots have a backup handheld comm radio, and perhaps a handheld GPS receiver. Some go further, organizing emergency equipment in a “grab bag” and occasionally reaching for it when all is calm, just to rehearse their act.
One good idea is to relegate a retired headset (or one you can buy cheap on eBay) to emergency backup duty. Besides the hands-free element, which can be vital in an emergency, it’s all but impossible to hear that handheld in a loud cockpit. It’s a lot easier to slip off the primary and slip on the already-plugged-in backup than it is to switch plugs around when tensions are high. If you fly at night, add a headset-mounted mini-flashlight in your arsenal (duct tape works fine).