To an extent I can apply my knowledge to other engines, sure. I’m working on my third Unreal project currently, and while it’s not like starting from scratch, I’m definitely way slower working with it. It also doesn’t replace Unity completely. It’s great for high-spec 3D stuff, but almost useless for mobile 3D/AR apps, which is a lot of what I do (not making games but mainly industrial interactive 3d applications).