The two games have very different mechanics. Both reward you for fighting smart rather than hard but unlike Don't starve, Valheim isn't a survival game where you have to do constant maintenance/progression to survive your surroundings and fighting hard can also be rewarded as long as you manage your stamina well. You don't starve to death without food in Valheim, though without food bonuses your base health is a paltry 25 which makes it pretty easy to get murdered by a simple mistake or being in the wrong place at the wrong time. You can progress at your own pace, as the difficulty scaling is based on which biome you are currently in and which bosses you have defeated so it simply won't get harder until you start doing things to make it harder. If you want to spend your first 100 in game days just relaxing and building in the relatively safe meadows biome, that's perfectly fine to do. Though be aware since you plan to play with a friend, when it comes to boss progression it doesn't matter if everyone has gotten that far together. So if your friend decides to go kill a boss without you, the raids can still get harder for you despite you not beating that boss as well. Chances are you plan to progress together though, so it's not likely to be an issue and having shield brothers/sisters can make everything slightly easier.