There is no direct support in REXYGEN for reading the Raspberry Pi System Information.
However I can imagine using Python script to read out the desired information (i.e. http://cagewebdev.com/raspberry-pi-showing-some-system-info-with-a-python-script/) and write it via REST API into REXYGEN algorithm.
Have a look at example 0302-03_REST_API_Python_Bash_etc, which will help you with REXYGEN REST API integration.
Hope the above is useful for you.