Each team will have its own unique user and channel namespace so email@example.com will be distinct from firstname.lastname@example.org. This is the same approach as email/matrix/fediverse.
If example.com bans #channel, that ban will not affect #channel on domain.net. A ban of email@example.com does not affect firstname.lastname@example.org.
Each team will run its own IRC services. This will prevent complete centralized control of services while also ensuring better redundancy.
The best way to achieve federation is to have separate networks linked together using an IRC relay. This would require the fewest changes to ngircd.