And that is the difference between a live service game and not.

Live service games tend to continue to trickle new content to players over time so they will always have a way to progress their characters while games like Valheim (or Subnautica, The Long Dark, etc.), even as sand-boxy as they are, have a defined end to their story.

But for many that 'story' and progressing to its end does not comprise their whole game experience and that is where the sandbox comes in. For example they may be builders and they still enjoy creating long after having finished the 'story'.

If you are a player that thrives on progression then probably your only meaningful options are to start a new game or wait for more content.