Do concepts add much value to a UXers portfolio?

I’m currently trying to build up a UX portfolio and I’m wondering if it’s worth my while adding in app concepts that I probably won’t build. Assuming it’s a viable app that solves a real problem for real people, is it worth putting in the time to take it as far as say high fidelity designs or a clickable prototype and leave it at that.

My background is in web design, though I’m not familiar with building apps. My typical web projects would be quite small, so there’s not a great deal to elaborate on in terms of UX. I feel like coming up with app ideas and fleshing them out would give me the most bang for my buck in terms of UX deliverables for a portfolio.

It’s probably fine to have a few app concepts but employers ultimately want to see more high fidelity wireframes and prototypes. Extra brownie points for completed projects.