I used to walk a similar distance to work. Things I always had with me:

good quality walking shoes (not runners or hikers, but real walking shoes) - they’re usually a bit more expensive but worth it. And avoid anything with a mixed sole with a logo on it - you’ll wear through the softer rubber of the logo and then it’ll start sucking up water into the shoe.

A comfortable backpack that can carry everything you need to carry

A brimmed hat (I found a full brimmed hat was usually better than a baseball cap)

A jacket appropriate for the place you live.

A bottle of water

A snack

Something high-vis. Doesn’t have to be a vest; an armband or something on your backpack is good enough.

Sunglasses. Get blue blockers for cloudy weather and polarized glasses for sunny weather. They’ll keep stuff from cars driving by out of your eyes. I found cycling glasses worked well.

And keep a change of clothes at work, just in case.