Hi,
have you considered implementing webauthn in Kee?
Here is how KeePassXC has implemented in their browser addon:
Sorry for the short post, currently travelling. I can provide a little bit more details if required. 
Bump!
Will passkeys be implemented? Would be much appreciated.
I just wanted to bump the topic myself, what a coincidence. ^^
actually i only use kee+keepass for convenience at work – there i can unlock my keepass with my corperate smartcard, which so far only original keepass supports (via plugin). i am also not entirely sure whether other keepass support native ssh-agent on windows (but at least keepassxc does). At work it would be quite awesome to integrate it into the project infrastructures.
on my private devices i mainly use keepassxc and and their plugin (without any webauthn so far, though) and keepassdx.
I’ve been considering this for a few years now and recently started experimenting with a few changes that need to happen before we can implement anything but I don’t know if or when I’ll have time to define exactly how we want Kee to behave with this new type of credential. When I looked only a few months ago it seemed like the browser support for extensions integrating with Passkeys was insufficient but hopefully support is rapidly improving so I’ll definitely take a fresh look at the possibilities this year.