I initially bought Valheim to check it out for playing multiplayer with family...

I couldn't wait for the requisite birthdays to happen and have already logged over 400 hours solo, but looking forward to starting over with a group soon!

So I think solo works out just fine! As someone else said maybe more "grindy" -- for me it just meant putting more time into preparation, having fun the whole time. I think of "grind" as when I'm doing something in a game that's tedious. I haven't found anything about Valheim tedious -- though I even have fun sailing... okay, sailing back to my corpse on the other side of the world while ill-equipped is not exactly fun -- but it's nerve-wracking and emotional, not grindy. :)