It's in beta, but seems to work pretty well.
Vikɪɴg survive-em-ᴜᴘ Valʜᴇim alʀᴇᴀᴅy hᴀs a ᴘʀᴇᴛᴛʏ ɢᴏod ꜰɪʀsᴛ-persᴏɴ mod, ᴀɴd ɴᴏw tʜᴇre's a mod ꜰᴏʀ virtual ʀᴇᴀʟɪᴛy ᴀs ᴡᴇll. Tʜᴇ wᴏʀk ᴏꜰ Brᴀɴᴅᴏn Moᴜssᴇᴀu, VHVR ɪs ᴄᴜʀʀᴇɴᴛly ᴇxᴘᴇʀɪᴍᴇɴᴛal, ʙᴜᴛ ʏᴏᴜ cᴀɴ ᴅᴏwnload ɪᴛ ᴛᴏ ᴛʀʏ ꜰᴏʀ yᴏᴜʀsᴇʟꜰ. VHVR ɪs ᴅᴇsɪɢɴed ꜰᴏʀ seᴀᴛed pʟᴀʏ wɪᴛh moᴜse-ᴀɴd-ᴋᴇʏʙᴏᴀʀᴅ, ᴀɴd tʜᴇre's ɴᴏ optiᴏɴ ꜰᴏʀ a ᴛʜɪʀᴅ-persᴏɴ ᴠɪᴇᴡ, ʙᴜᴛ ᴍᴏᴛɪᴏɴ ᴄᴏɴᴛʀᴏʟ sᴜᴘpᴏʀt ɪs ɪɴ tʜᴇ wᴏʀks.
You'll still be able to play in multiplayer whether your friends are using the VR mod or not, but you will need to turn off anti-aliasing and bloom, and it's suggested you turn off motion blur as well. To get it working, grab the BepInEx framework, then follow the instructions at VHVR's NexusMods page.
Valheim joins a long list of flatscreen games that have gained VR functionality thanks to modders, like Alien: Isolation, Crysis, Half-Life 2, and basically every first-person shooter from the 1990s.
Here are the best Valheim mods.