I've seen that kind of comments multiple times, and I don't get it.
I use Yubikeys, and passkeys just work. On Chrome, Firefox and Safari, both on macOS and Linux (specifically Alpine). I also tried with iPhones (for my family), and it also just works.
I haven't tried using an Android device, is it what you are trying?
Could it be that your phone is not compatible with passkeys? E.g. many Android phones don't have a TPM, isn't that a requirement for passkeys on Android?
As I said, it just works with iPhones and Yubikeys.
I use Yubikeys, and passkeys just work. On Chrome, Firefox and Safari, both on macOS and Linux (specifically Alpine). I also tried with iPhones (for my family), and it also just works.
I haven't tried using an Android device, is it what you are trying?