Nope as far as I know it's impossible - there is no standard yet for exporting/importing keys. Thinking also, Apple would not want to go with that - it would be like letting iMessage run on Android. So what I've been advising is to use passkeys with a service that will follow you across devices and OSs. In my case I'm using Bitwarden, but I think 1password (or similar) is also doing it.
Should I be using passkeys on my Apple devices when websites offer it? I’ve heard they are good (basically public key crypto) but I’ve also heard that the way Apple and Google are implementing them promotes ecosystem lock-in. Does anyone know if it’s easy/possible to move a passkey from an Apple device to a non-Apple one? CC nostr:npub1g2jpj7x9rjcqd9dp3hnvja2tjr3q3hf362z3ulrfzpyfnsdw5qlqyayjj6 I feel like you might know about this.
Discussion
I guess that’s how they treat iCloud keychain also, no good export. It seems like it really limits their utility though.
Yes, it does if you want to move outside the Apple ecosystem. That's where the Apple and Google philosophies differ a bit. Apple is amazingly good if you just stick to their products, but that makes changing away really difficult.
I actually exited iOS quite easily last year, but mainly because I did not really use any Apple products on iOS. I love cross-platform as I know I have more freedom of movement and choice.