While the two games could not be farther apart in of setting and genre, Valheim share a very important feature in the form of their base-building. Both ask players to gather raw materials in the hopes of propping up homesteads, whether it is across a post-apocalyptic Boston or a Viking-themed afterlife. There are enough similarities between the two that Valheim should definitely take some lessons from Fallout 4's settlement system, both on what to do and on what not to include.
Valheim already has one huge advantage over Fallout 4, and that is that there is no electricity in the Viking realm. Running powerlines across settlements in Fallout was an enormous pain. Trying to snipe the exact spot to attach a cable to a router became a common, infuriating issue. Beyond just power infrastructure, Valheim should avoid the fiddly construction issues that arose from needing to precisely connect small pieces in Fallout 4. So far, the game's generous snap-to system has been good at alleviating that issue - even when building some truly jaw-dropping Valheim constructions - but it should remain a focus of future Early Access updates.
A major benefit to spending time building up settlements in Fallout was the ability to recruit followers to take care of the more mundane aspects of everyday life. Having a ghoul-run tarberry farm at The Slog meant that there was always food available for the player to grab in Fallout. Making some sort of worker available to farm or refine basic resources would be an excellent addition. Players can already tame boars and other wild animals in Valheim, so maybe there could be a way to press-gang Greydwarfs into service? That may take the game into uncomfortable, forced-labor territory, but it's not like the world of Valheim is all sunshine and rainbows as is.
Valheim Should Learn From Fallout 4's Settlements
One of the most annoying parts of the base-building system in Fallout 4 was how isolated each individual settlement was. There was no shared resource pool - not until players unlocked a perk that allowed them to set up trade routes, that is. After that, building and maintaining multiple homes become both easier and more advantageous.
The world of Valheim is huge, and having multiple bases is pretty much a necessity. Building roads is already key in Valheim, but what if players could attach a cart to a tame boar, fill it up with rocks and wood, and ship it off to another of their bases? A trade route, or other resource sharing system, is something that should be added to the game.
Valheim may have already learned a few important lessons from Fallout 4's base-building, like having raiders (or trolls, in this case) attack player's bases, but there is still plenty it can incorporate while in Early Access. By taking the best part of Fallout 4's settlement system and ignoring the worst, building in Valheim could be a truly magnificent experience.