I'd say that anything you create and you want to create will be a good for you, both for your professional life, but just as importantly (perhaps more) for you personal life.
As to where you should dedicate your efforts, well, yourself. It's important to enjoy your hobby, even if you want to spend your free time creating something fairly useless, whether it's a transistor clock of your own design, your own CPU architecture or a steampunk multimeter.
And do not be deceived - even such (or especially such?) frivolous applications will teach you more than you'd expect. And if you give me three engineers to choose from, all with equal resumes but one shows me his transistor clock then it's a clear choice for me which one to hire.
However, if you want to go in a specific direction, I'd say go with things that have broad applications. Focusing on the latest web 5.0 framework that's in vogue this year is all well and good, but learning to work with FPGAs is better and looks better on your resume. Try building something you want to build and applying a technology you've never worked with but seems fun into it. A line follower robot with five cameras, powered by an FPGA or something like NVidia Jetson is delightfully useless and total overkill, but will teach you sooo much.
And don't forget to enjoy things outside of electronics.