The problem is that big companies don't want them to be as versatile. They don't trust us to manage our credentials.

Hence FIDO2 and Passkeys feature 'attestation' that allows them to only accept 'trusted' implementations. This accreditation is a crypto process so it can't be faked.

So, you can't just put your keys in any app you wish, like you can with TOTP. There will be strong pressure to just 'go with the flow' eg mainstream OS implementations and us with niche OS or cross platform requirements will be ever more marginalized.

Any complaints will be simply rebuked with "For security reasons" or "We only certify implementation X, Y and Z".

My work is already doing this, they only support Yubikey and one other brand through their Identity Provider, if you have one of the open source tokens you're straight out of luck. Passkeys don't work yet either but I'm sure they will only 'certify' Apple and Microsoft and leave the rest hanging. They love quoting the pareto principle / 80/20 rule as an excuse.