I looked and Python has the library support for the GPIO and to do background threading to poll pins. My preference would be to go with a JVM language like Kotlin, but then I’m a programmer. Python, from the little that I’ve mucked about with it is really just one step in complexity from scripting. Maybe even easier, because some things in shell scripts are super difficult to do.
Technically, he would have three drives and only two drives of data. So he could move 1/3 of the data off each of the two drives onto the third and then start off with RAID 5 across the remaining 1/3 of each drive.