How do I check the current version of the PDK installed on PX2 as well as the Aurix version?
you could check the software release via sysnode,
$ cat /etc/nvidia/version-ubuntu-rootfs.txt
or you could connect the DrivePX2 to your host device, entering Aurix shell with serial console.
$ picocom -b 115200 /dev/ttyUSB1 ... Terminal ready shell> shell> version Info: Executing cmd: version, argc: 0, args: SW Version: DRIVE-V5.0.10-P2379-EB-Aurix-With3LSS-4.02.04 Compilation date: Aug 13 2018, 21:48:18