over 3 years ago - Munin - Direct link
Yes, there is a test branch available, but it's private (more or less).

To get access you need to join our Discord, go to #rules-and-info, react with "V" (:Valheim:). Then go to the channel #valheim-public-test and read the pinned messages on how to activate the test branch. You can also provide feedback and discuss changes in that channel.
over 3 years ago - Munin - Direct link
Iron Gate also uses the test branch option via Steam. But it is a private test branch which requires a password. The only way to get access is how I described, after that you could theoretically deinstall Discord again.