This^^^ I have loads spare but it will be a while before i could drop you a couple in the post.
also be careful as the Asrockrack screws for NVME are not the same. The part numbers i have are: 13G020647022AK
You could try emailing Asrock support and they might just send you some. If you dont get any luck i can post you a couple after about the 14th of may.
BTW i know the newer Asrock boards use a standoff that has a built in plastic hold down or they use the heatsink to hold down the drive worth checking that first..