Looks like a huge amount of security vendors are working to have a secure and open standard for passkey portability between platforms.
It is always good to see major collaboration in the security space like this considering the harsh opinions that users of some of these vendors have toward many of the others. I just wish apps and sites would stop making me login with username and password if passkeys are meant to replace that lol.
Keepass is a style of encrypted file with a list of the passwords and the syntax is standardised. There are many apps/programs for any platform that offer pw management based on that file. I use keepassXC app on linux and strongbox on iOS since both of them are well integrated into the operating systems. On ios i use the webDav protocol to sync the keepass file on my server with strongbox app. On Linux I use nextcloud sync to mount my files on the server into linux and in keepassXC I have set it to automatically grab that keepass file on boot. Ah of course the keypass file is protected by a strong password, but this could as well be a hardware token like a yubikey. But if you have a yubikey, you just store your passkeys on that😂