Adding an office shed in our backyard. What add ons should I consider in the design process?

Long story short, we’re building an office space (around 10x12’) in our backyard so we have more bedrooms available in our house for actually living in. It’ll have all the works— electric, heating and cooling, insulation, flooring/paint/baseboards, etc.

We meet with the designer to iron out final details next week and I’m trying to think of any final touches I might want to add to the build before all is said and done. My husband does gunsmithing projects, so I might add a wall safe to store his guns so that we have extra storage for that without taking up floor space. We might also add a doggy door so that our dog can go in and out as he pleases. Any other ideas of things that might be beneficial— and would be harder to add on later if we don’t do it now?