The gigabyte site had a note where m.2 support only works on Athlon CPUs. Help, me noob.
https://www.gigabyte.com/ph/Motherboard/B450M-DS3H-rev-10#kf
https://www.gigabyte.com/ph/Motherboard/B450M-DS3H-rev-10#kf
No, that's not what it is saying.
With an Athlon CPU, it can use only a SATA M.2 drive.
With a Ryzen, it can use either a SATA or NVMe drive in that M.2 port.