You can’t share passkeys yet, but this feature is in development. For the time being, many websites and apps support both passkeys and passwords, so you can share a password if you want someone else to access your account.
You can move passkeys between Dashlane and Apple Passwords, 1Password, Bitwarden, or any other third-party iOS app that supports Credential Exchange.
Credential Exchange is part of a broader industry push for open standards. This approach gives you more control and flexibility. Dashlane and other companies aim to make passkey import and export possible between password managers as well.
More about Credential Exchange
You can't export passkeys using CSV files or back them up with DASH files.