Anyway, the less impacting version for Pi Cluster in the range of commercial choices, in my opinion, it is the Bitscope. With a few visible patches you avoid losing the 40 pin GPIO connector.
Thinking to a Pi cluster (as I have done, based on 4 Pi 4) in an IoT environment you have plenty of simple sensors inputs and eventually controls while the huge data can be processed at higher speed thanks to the clustering approach. A single node can also include some extra hardware input without seriously impacting the process performances.
verPI by IPTerra – Take your Raspberry Pi to the next level!!! 
