Yes, one SATA port and one M.2 internally. Ideally you’d want matching (like two M.2 drives) but it’ll still work fine in btrfs/RAID
Discussion
Ah actually the higher-end Optiplex Micros (5000 series) do have two M.2 slots for SSDs and still have one SATA, though they’re a bit more expensive
Actually ideally you don't want the drive types to match. Two different drive brands and interface types are less likely to experience a random failure simultaneously.