They are easily exportable from Apple and 1Password AFAIK. Bitwarden seems to be doing some interesting lock-in, and while I have loved them, I no longer have a commercial password manager that I trust (leaving me with only Apple's as a high-functioning, high-trust option). I'm worried about effects of private equity pressure on groups like 1Password, Bitwarden, and LastPass (I strongly recommend against LastPass these days).

Bitwarden's format is at least implicitly documented via their open-source clients, and as a sibling comment already has mentioned, their data export includes all private/secret key material.

Actually, if you export your vault as JSON, the passkeys are there in plain-text.