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😂