BIMI is a branding layer built on top of authenticated mail. Supporting mailbox providers may display a brand-controlled logo when the sender meets their requirements.
BIMI should come after the authentication work. A domain needs strong DMARC deployment, and mailbox providers can impose additional requirements such as reputation and an eligible mark certificate.
It is not an anti-phishing replacement. SPF, DKIM, DMARC, account security and filtering still do the security work.
Provider support and certificate requirements change, so verify current mailbox-provider requirements before buying a certificate or planning a rollout.