X520-DA2 does not ship with any optics, if you need only one port. you can go with X520-SR1 or X520-LR1 depending on your switch (SR or LR). sharing a link below for your reference.
for X520-DA1 OCP (Open Compute Project), it has a different physical form factor compared to X520-DA2. kindly refer to the link below for picture of X520-DA1 OCP.
hope this help.