6 Raspberry Pis, 6 SSDs on a Mini ITX Motherboard
A few months ago someone told me about a new Raspberry Pi Compute Module 4 cluster board, the DeskPi Super6c.
You may have heard of another Pi CM4 cluster board, the Turing Pi 2, but that board is not yet shipping. It had a very successful Kickstarter campaign, but production has been delayed due to parts shortages.