My customization of linux begins from theming the grub. Even after trying and using many great grub themes, I was not able to settle on any theme. All of them were great. But, none of them ignite a feeling of, this is the one I am looking for. Also, I wanted some level of personalization such as my username/name on it. So I myself tried to create one and the result is sleek grub themes which is minimal, beautiful and elegent.
Sleek Grub Bootloader Themes has 3 color options "Dark" ,"Light" and "Orange" [I don't know why i choosed this color but it looks beautiful] and one macOs inspired theme with BigSur wallpaper. If you want to have a feeling of belonging, You can have your name on grub bootloader.