I use a Tecla to control my phone, and that’s great, (but it’s also pretty expensive). I just sort of realised that my bluetooth earpiece, which I use because I can’t hold my phone up to my ear, er, obviously, has another VERY useful property: you can answer the phone by clicking it.
Now, obviously you’re meant to use your hand to do this but as this particular model only goes a little bit into your ear - it’s held on by an earclip instead of being wedged right into your ear canal - you can press the button by pressing your head against your headrest or pillow. So you can answer and hang up the phone JUST with this earpiece. It’s like £10. It’s the cheapest accessible phone input device I’ve ever HEARD of.
Make sure you get this model:
There are similar earpieces where they’ve recessed the button a little into a hard plastic surround, so it’s much harder to press. And another one that doesn’t have an ear hook or any way to attach one, which will drive you bananas when it falls out and you have to wait until a pair of hands comes along to put it back in for you. So I specifically recommend this model. Even though the “voice control” is rubbish. (You can always buy ear hooks separately, though, if you prefer another model but still want the hook.)
Unfortunately you can’t pair this and add it as a switch input, though you really should be able to, right? But it’s not recognised.