I accidentally found another set of interesting icons on the net called Phosphor, which includes about 600 icons (MIT License) and I prepared them for uploading into Oxygen. You can check the full list of icons on the Phosphor website.
Download Phosphor Icons Set: phosphor-symbol-defs.svg.
In a previous article, I talked about how you can upload your own set of icons to Oxygen using the Unicons icon set as an example. Just repeat the same steps.
After uploading into Oxygen, a new set should appear in your list of icons: