Hit The Woodline
Are you mainly living out of a rucksack or are you using a pulk? I have an entire loadout with a pulk/sled that has drastically improved long term sustainability in cold conditions. I also have found that having a lighter pack (40-50L) rather than a super large one also helps while snowshoeing or cross country skiing to make up some distance while not yeti bogged down.
For all of my loadouts I pretty much revolve around the core categories of "food, water, fire, shelter, hygiene"
In winter/cold I'll generally try to stay away from anything that can harden considerably in the cold. Like first strike bars in MREs. I also try to have a decent mix of hot water meals and ready to eat meals. That way I can have comfort meals as well as on the move meals that don't require fire or fuel.
For water, boiling snow is the easiest way to get clean water in a sustainable way, but normal water filter is also carried.
Fire I keep bic lighters in my pants and jacket pockets to stay warm, zippo with fuel, and ferro rod for combustion devices, and I generally keep a small sealed bag with birch bark I'll collect and replenish when possible.
Shelter is a big thing. I generally will pack a pair of socks for each day with an extra heavy "night time" pair. Layers suited around sitting static at night with the ability to strip down while moving. Generally will have a base merino wool layer, and fleece or loft jackets with a shell on the outside. For sleep I use a 17 degree bag, swagman roll, and goretex bivvy. Tarp for my main shelter. Beanie and multiple sets of gloves. Booties would be nice to have at night but I haven't gotten around to getting any.
All in all I can cram most of this in my DG3 for a weekend trip, but require a larger ruck for longer trips. FILBE is my only current larger ruck, so I use that if I need to.