I went this route. 1st NVMe has the O/S and common desktop apps. 2nd NVMe is dedicated to the VR flights sims. And because I had the 3rd NVMe slot available, my 3rd is for swap (for now). I have a fourth SSD, (2 TB), that I dump all of my Steam and other games onto...
But if you have 2 drives, go with what Rudel_chw noted. the O/S and swap on the 1st, and dedicate the 2nd drive for DCS.