In start of 2nd year and have already made a distro(OS), many apps, 3d websites and stuff, suggest me more difficult projects or niche ones pls

I want to make more projects which are harder now, like way harder, currently making an ARM based OS or porting my OS onto ARM based devices, I want to do more hard stuff and even make something much newer, u are open to give suggestions or any idea like ANY u would deem as hard