I would like to see secret permanent perks. Something I enjoyed in the early Fallout games was the secret perks. These were perks you could get by doing certain quests or doing certain things and wouldn't show up as a reward but you'd just get them.

For Valheim these perks could be. extra 50 lbs carry weight, because you spent X amount of time walking while encumbered.

Lose 25% less stamina while swimming received because you spent X amount of time swimming in a storm.

Harvest extra berries and mushrooms because you harvested over 75 different things on the ground.

Build a ship with less resources,received from having two different ships get destroyed.