Items that I use on a regular basis, daily life, etc. that also double as backpacking items:
Pack. I have a simple rucksack made by Christopher Zimmer that is simple, functional, and really durable. This is my backpacking pack and my grab and go pack used daily, always beside me in the car, my mobile locker and general gear hauler for work, running and riding.
long handled titanium spoon. Lives inside my pack and gets used almost every morning with breakfast, post run or ride.
Petzl XP2 or BD Storm headlamp, whichever one I can find and has battery life- For the darker/shorter days I use my headlamp almost daily, whether that is for a morning trail run or evening, especially in Dec.-Feb.
Merino socks- I don't discriminate, the same Darn Tough or Defeet merino socks are on my feet year round, they get used for all occasions. I'm a trade worker who works in jeans and boots though, so it's not a stretch. If I were a suit and desk riding jockey I would probably still wear my same merino socks.
Patagonia Nano puff hoody- it's about ideal for the temps here in southern NM, it is in my vehicle most of the "winter", gets thrown on immediately after a run in the morning, or with me at work.
CCF sleeping pad (ridgerest or Gossamer gear nightlight)- I have one of these in my daily pack that goes out the door with me during the week, it gives my pack some structure and also gets thrown on the desert ground when I change clothes post workout. Everyone should have one in their vehicle.
Windshell. Always in my pack, gets thrown on whenever I need it.
Classic specialized mtn bike water bottle. I take one for backpacking trips mounted on strap, trail running, mtn biking, around work to stay hydrated.
Buff (merino)- I own two of them in wool and alternate through them during the colder months. They're great for everything.
Sunglasses. I wear the same pair of shades for all purposes. Either a Rayban wayfarer, or my Native shades.