Would interest me, too. (I haven't given up yet on using the MS-01 as an M.2-based Unraid server/NAS.) We have discussed the PCB length earlier, and 22110 cards are too long, but 2280 should work, so in theory you would be able to add a card with four M.2 NVMe 2280 SSDs running at x2 speeds. You'd need a card with a PCB that you can break off at the end. However, one user already wrote that the clearance beneath might be too small, so with the two M.2 SSDs on the underside it might not fit. But someone would have to test it. Another important issue would be the heat. Using four gen3 SSDs at x2 speeds, which is the logical choice for a RAID setup together with the other built-in slots, would not produce as much heat, especially if you add one or two of those USB-powered external fans. However, that would still leave the two SSDs on the underside of the card, which I'm sure would run at higher temperatures than the other two, even with an additional fan. (Provided they fit at all.) It might work, it might not… we won't know until someone runs a few tests.