PMU is a software that implements IEEE Std C37.118.2-2011 using A Raspberry Pi. The communication is implemented using SPI protocol. So Any device that would be able to communicate with SPI can be used as a feed for data.
This was tested using Arduino (The actual implementation was supposed to be run on FPGA, the work is yet to be complete).
You would be able to run the PMU software on a computer. If the software doesn’t find any SPI port, a single set of fake data is generated just to show that the software is working.