But what if your garmin is connected to your phone with data connection you can use that data connection to make the auto catcher and auto pokestopspinner work.
Can someone make this?
No. And even, if someone could, it would be rather useless, since you'd need a phone for the data connection anyway (there is only one Garmin device with LTE - the Forerunner 945 LTE). And if you have a phone with you, it is much easier to use the phone for the Pokemon detection, isn't it?