I think we posted at the same time. I just didn't know how to pass it through, lol.
With the 896660 -beta public-test -betapassword "yesimadebackups" as the GAME_ID variable I am getting
Loading Steam API...OK
Connecting anonymously to Steam Public...OK
Waiting for client config...OK
Waiting for user info...OK
ERROR! Password check for AppId 896660 returned error Failure.
In the log
EDIT: Setting GAME_ID variable to
896660 -beta public-test -betapassword yesimadebackups
(Removed the quotes) resolves the issues. Cheers all, thanks for Valheim docker and the help Ich777!