Unlike some other survival games like ARC or Conan Valheim is not too grindy solo. You can do anything you want in a reasonable time alone. Of course, most of the content is easier with others as long as they are not jerks.
I did not really check myself, but I get an impression that Valheim community is not overly toxic to new players, so it should be easy enough to find normal people to play with if you wish.