Was thinking of putting a newly spare M2 SATA III drive in the 2nd M2 slot, but it is 2260 form factor. That's not supported, right?
My NUC is: NUC8i7HVK
Paraphrasing, the board design does not include a mounting post for 2260 modules.
You might be able to use an adapter like this: https://www.amazon.com/Black-Flexiable-Extender-Adapter-Screw/dp/B01E75ZJMW https://www.amazon.com/Black-Flexiable-Extender-Adapter-Screw/dp/B01E75ZJMW or this: https://www.ebay.com/itm/M-2-NGFF-NVMe-SSD-2230-2242-2260-2280-Length-Extend-Adapter-Bracket-Card-Pl... M.2 NGFF NVMe SSD 2230 2242 2260 2280 Length Extend Adapter Bracket Card Plate | eBay to mount it.
Hope this helps,
It's only a 128GB drive, so I probaby won't go to the effort of buying a adapter for it. And I guess I will find a better use for the second slot anyway