You are missing the point. None of that can be added. It's not an fp. It doesn't even have a hotshot and there's no EVF nor 'everything else' as add-on. Only

You are missing the point. None of that can be added. It's not an fp. It doesn't even have a hotshot and there's no EVF nor 'everything else' as add-on. Only changeable things are L-mount lens and battery