Up in the wilds of Sweden I'd go for reindeer rather than moose. Lot easier to drag back to camp.
Problem with living off the land is there are lots of things in the land that want to live off you. The reindeer will likely have worms, rodents are almost guaranteed to have some kind of parasites, occasionally rabies, and the smaller birds are simply not worth the effort. Even the fish you mentioned need proper cooking. Do you already know how to butcher small game? Cleaning fish is easy, skinning a beaver is not.
If your end goal is weight reduction you need to consider the balance of packaged food against fuel. Yes, you can get fuel off the land but not if it's been raining. Gas burners will quickly boil a litre of water for a packaged dinner without having to gather and build the campfire you would need to cook today's catch. Also consider the time spent hunting unless, again, that's the point.
Berry picking will also take a lot of time - are there edible berries in that area, are they in season, can you tell the difference between edible and inedible? Forget mushrooms unless you can positively identify each one that can survive a Scandinavian winter. And by identify I mean "here is a kilogram of mushrooms. Put all the edible ones in this pan, all the poisonous ones in that pan. You have one minute.
If you do go the wilderness route, book a doctor's appointment for when you return. Worms, parasites, tick-borne diseases, heavy-metal levels. A veterinarian might be better than a city doctor.
- stay far away from rabbits. Especially white ones living in caves.
- A wild animal with no apparent fear of humans likely has terminal rabies. Yes, Sweden is rabies-free but others might read this in the future.