While your OWC SSD will work, it won’t be very fast as its only a SATA II (3.0 Gb/s) Vs what this system can support either a SATA III (6.0 Gb/s) or via a 8.0 GT/s NVMe/PCIe x4 blade SSD.
Remember you can’t use the Fusion Drive’s blade SSD with your OWC 2 TB SSD in a Fusion Drive set.
I would recommend getting an external drive case USB or USB-C/TB3 to hold your OWC drive and call it a day.
If you want to really want to goose your systems performance I would break the Fusion Drive set, take out the PCIe cache drive and put in a 512 GB or larger blade SSD like: [https://eshop.macsales.com/item/OWC/S3DAPT4MA10K/|OWC Aura Pro X2]