Whitelisting and Blacklisting, user pre-approval/pre-denial by database storage

A functionality, or Integration/'bot', to create a database of usernames that are either pre-approved or pre-denied access to a server.

A common security tactic of publicly findable servers is the tech literacy test that requires users to add their own roles or agree to Terms before being able to view main forums and such, but in cases where users can't be trusted to Role React for themselves, it means Admins and Mods busting their asses to manually assign roles and permissions to new members individually as they join the server.

A browser-based control dashboard where a username or email database could be kept for users who may not have yet joined the server (but an invite has been sent to them directly) would really speed up the process, while eliminating link sharing on outward from the person who was specifically invited.

• A user subscribes to paid content on another platform, and includes their email address in their registration/purchase. Their email address goes in the database. When they attempt to join the server, their email address is recognized and they are automatically 'fast tracked' past the security waiting, and even added to roles relating to their subscription level.
• An organization is having an online convention which starts and ends on a certain date, with paid registration. Prospective attendees submit their registration, including their user#0000. This is loaded into a database so that when the convention starts and the server "opens" by sharing the link to all registrants, they can't then pass along their invite to their friends because only their user#0000 has been pre-approved as a member. Now, moderators don't have to rush to give all the rapidly joining server members their roles in a matter of hours, because they were auto-assigned in the database during the weeks or months leading up to the start date.
• A popular content creator has long operated a successful fanbase server. They've had to ban some folks here and there, but it's time to expand to a second server for a more niche group of the base. The list of bans from the primary server can be imported as a pre-denied blacklist, preventing those user#0000s from joining.

I'm sure there are more examples, but those are the ones that came to mind. Automation that excites?