IMO, clipless pedals and shoes are one of the single best upgrades you can do. Especially for me with one bad knee, I like knowing my shoe is always exactly where it needs to be. Pedal feel increases significantly, you feel much more in tune with the bike. But you generally give up some walking comfort, but not always. You can get commuter or "spin class shoes" which give up some stiffness for flexibility and ease of walking. Most performance minded shoes will be stiff, and shaped in a way to where you duck walk a bit, even if the cleat is recessed. Mtb shoes and pedals are a must, road bike shoes are Luke walking on ice in high heels

I strongly recommend trying some on at your lbs and trying to walk around. Most brands will have an option or two that are geared more towards walking. Try a few on. I can walk around in stiff mtb shoes to run into a store or a bar, but I probably wouldn't want to walk around a shopping mall or festival all day with them.

You might be able to find a pair of lightweight and/or folding slip on shoes that you can put in an empty water bottle cage, or store under your saddle bag or something and do a quick switch when you need to walk around. I do this with sandals in the summer.