No point in getting a M.2 SATA drive unless it's specifically to go in a M.2 slot that supports only SATA. I don't know if there are many M.2 slots on motherboards like that. Most support either NVMe or SATA. Best check the motherboard manual first though, just to be sure.
There is a small cost difference, depending on which brands you're looking at, but it's not large enough to warrant buying a M.2 SATA over NVMe; especially not when you've got a NVMe already and another will give you really fast transfer speeds between them.