Linux Mint isn’t the only distribution that wants to use its own custom Nautilus; SolusOS 2, a Debian-based Linux distribution currently in alpha that uses the GNOME fallback session as default, uses a customized Nautilus too.
It’s not a fork but it comes with some cool patches that bring an unified, customizable toolbar with the back/forward buttons on the left, as well as some smaller patches like for instance a patch to restore the ability to create a .desktop launcher from the Nautilus context menu.