It makes sense to go with NVMe drives instead for a RAID NAS as it’s the same memory technology (and what mostly determines the price in all of them is the amount of memory) so the price per GB isn’t any higher (probably a bit lower as size is less of a constraint), the size is still quite small (it’s surprising just how small NVMe SSD drives are compared with the older SSD 2.5 inch SATA ones) and NVMe is a much faster interface than SD so that things is going to be way faster.
It think I saw some in AliExpress the other day, but for what I use my NAS, plain old HDs with no RAID for redundancy or speed are just fine.