The second key we need to encode into the QR code during secondary device login is the ed25519 key, identified as the device id.
After speaking with @marcin and @kamil (and office hours yesterday), accessing this via the commCoreModule on native is done by making a commCoreModule.getUserPublicKey() call, returning both a ed25519 and curve25519 keypair - the first is the one we need.
On web, it's a little different. @kamil pointed out the way we currently do it is by accessing it through Redux, and it seems like the only way to access the keys for now. I won't need to worry about running the key generation protocol since key generation occurs when the login form is rendered. Since the QR code login screen is accessed by clicking a button on the login form, we know the keys should exist.
Depends on D9093