It’s main advantage, as far as I can tell, is having a much simpler interface. It’s snapping tools are trivial to use and discover, but far less robust than Krita’s assistant tool. It’s easier to add brushes, but you have far less options in configuring them. I don’t thinks there’s anything that Firealpaca can do that’s partially hard to do in Krita. Also, Firealpaca doesn’t have a dark mode.
I’m not an experienced artist though, so take my opinion with a grain of salt.