Amazing ideas from everyone! I finally first time read https://www.behance.net/gallery/27500387/TOHKBD-The-Other-Half-Keyboard-for-Jolla-Smartphone# TOHKBD and I must say that I would buy out-sliding keyboard TOH with this layout in a instant. Personally I know I would never have it when I would like to use it and if it fits to my pocket I don’t think I would need to take it off.
Another practical use case for me would be the camera addition as I always get complains from my other half (with iphone) that pictures I took look low quality… Also amazing if the camera addition TOH could fit to male jean pocket. Don’t need to be that comfortable there, but as I don’t want to hang it on my neck I would prefer putting it to my pocket when I need to put the phone away.