The developer of checkra1n now creates a tool to turn your Raspberry Pi into a dongle to run checkra1n. You can run the Exploit over raspberry pi automatically and exploit the phone. when it is plugged in over USB. You could run an automatic python script that jailbreaks the device when it detects what it plugs in.
I’m no expert on Raspberry Pi , but on an abstract level you should be able to make a systemd service file (on a completely normal raspbian stock image) that polls for an iPhone’s USB connection or that triggers when it is connected (udev ought to work for this) and then runs a command on the trigger on the detected device which would ideally be checkra1n once ported to Linux. Perhaps you might need a execstartpre with libimobiledevice to give you the UDID for the specific identifiers checkra1n needs. It’s only an arm (cross) compile away once the code is ported to the Linux USB subsystems (likely libUSB).
Checkra1n on Raspberry PI