Bitbucket Server/DC should support security keys (like YubiKeys) for storing SSH keys. The two standards are ecdsa-sk and ed25519-sk

When trying to add a public ed25519-sk or ecdsa-sk key to Bitbucket Server/DC, the server reports: "You must enter a valid public key"

Tutorial to generate a SSH Key that supports a U2F key: How to configure SSH with YubiKey Security Keys U2F Authentication on Ubuntu