any Blender themes I either created or modified
3.1 themes may also work on 2.9.x, but no guarantees.
Nord Pro Scarlet is based on the Nord Dark theme for Blender and heavily modified. I might make other colour variants in the future.
December Dawn is made from scratch using Blender Light as a base. Some parts are still in progress, but the key features (node editor, properties, outliner) should be fully themed.
I recommend changing your Blender font, as the default font doesn't really do these themes justice. Free recommendations are Inter, PT Root UI, Work Sans, Lato, Red Hat Text and Cantarell; the one I personally use is Graphik.