Their 2017 PDF presentation has good info re: their current state:
https://github.com/Cosmos-OpenSSD/Cosmos-plus-OpenSSD/blob/m...
Page 10 shows the 3 generations of OpenSSD they've been developing. They're on the 3rd gen now (marked 2016), which is FPGA based, says it support a subset of NVMe, and mentions a 2TB max capacity.
Might be interesting to actually do stuff with. :)