In order to start using Wikimedia Chat instead of other instant messaging platforms already in use for Wikimedia projects ability to log in with Wikimedia unified login is an important argument. This makes Wikimedia Chat preferred suggestion for new Wikimedia volunteers, since they don't need to create any separate accounts from Wikipedia account they already have and they can avoid creating account on closed/commercial platforms like Slack etc. But it is also an argument to move to Wikimedia Chat for existing collaborators, who might otherwise be reluctant of stepping out of their comfort zone fixing something that ain't broken.
Direct registeration should also remain supported, for users who want to remain anonymous, those does not have an account or can not register one (e.g. because of block or interner censorship).
I voted, however I don't see how this aligns with their organizational focus (private cloud infrastructure) - have you considered taking generic OAuth bits from this fork?
(Right now I get a login form that doesn't say I can't use unified login, and no "create", which is liable to confuse.)