Add custom Hexidecimal-based color to solid colors on new tab page and dashboard

I would like to see the option to be able to add any hex custom solid color to the “solid colors” on a blank page tab or homepage. The solid colors options are limited to what the OS provides and I would like to be able to add my own hex color like #2B2B2B to match my OS in Linux Mint Dark-Y-Aqua for example. I can upload my own screenshot of a solid color currently but a “gradient effect” appears on the image like this which I do not want:

Either that I would like to just be able to customize the specific color for a blank tab page.