By integrated into the OS, I'm talking about the major corporate implementations, like Apple, Microsoft Windows, or Google Android. The advantage is that you don't need to install an app or browser extension, and then give that app permissions. Everything is already set up. I've seen some websites like Amazon try to automatically set up passkeys for you, so it's likely that a good portion of the population already has passkeys set up in these corporate passkey managers, before they have the opportunity to learn about alternatives.

Speaking of Keepass, you should check out these discussions:

https://github.com/keepassxreboot/keepassxc/issues/10407#issuecomment-1994673954

https://github.com/keepassxreboot/keepassxc/issues/10406

In short, keepass had a way of exporting passkeys unencrypted to disk, and some people did not like that, threatening things like:

This implementation is not spec compliant and has the potential to be blocked by relying parties.

The unfortunate piece is that your product choices can have both positive and negative impacts on the ecosystem as a whole. I've already heard rumblings that KeepassXC is likely to be featured in a few industry presentations that highlight security challenges with passkey providers, the need for functional and security certification, and the lack of identifying passkey provider attestation (which would allow RPs to block you, and something that I have previously rallied against but rethinking as of late because of these situations).

This is exactly what the "passkeys are a trap" article warned about. Passkey attestation allows websites to reject specific clients, just like how SafetyNet allows apps to block GrapheneOS users. In the future, banking websites or google.com could force usage of passkeys, and block usage of keepass. Are there enough keepass users to protest this? Certainly hasn't worked well for GrapheneOS and SafetyNet.

this seems to be an EEE scheme of Authy specifically

Functionally, it's locked down because it's nearly impossible to migrate the TOTP codes to another app.

You don't really see custom TOTP apps because users don't want to have to install an app just to generate TOTP codes for a specific website. Google Authenticator could have done this, but I think Google decided to start moving towards passkeys instead of enshittifying Google Authenticator.

There is much more incentive to do this with passkeys, because you can lock down passkey sharing in ways that can't be done with TOTP. For example, Netflix could block passkeys from any client that allows passkey copies and exports, like Keepass, in order to block account sharing.