You’re right, a lot of people have asked for this. But there isn’t a perfect, completely automated solution for it due to the security risk of automatically disarming the alarm and unlocking doors.
Geo-fences are great for automatically sending you reminders to arm the alarm and lock the doors when you leave but they can’t be used to automatically unlock doors.
The closest thing I can think of to this would be an automation that automatically unlocks the door when the alarm system is disarmed and using Bluetooth disarming on the IQ Panel 4 to disarm the alarm. But TBH people have reported mixed results with Bluetooth disarming. You would have to have a reliable Bluetooth connection from your garage to your panel.
The reason this use case isn’t supported very well is that Alarm.com really wants you to provide a credential (like a code or login) to securely disarm the alarm or unlock the door.
The most reliable solution for this would be to disarm with the Alarm.com app, CarPlay or Android Auto and have the door automatically unlock when the system is disarmed.
Which lock you use wouldn’t matter. Any Alarm.com-compatible lock would work.