Passkeys not working on PayPal, Keycloak, and Ebay

Regarding PayPal. I did a https://duckduckgo.com/?t=ffab&q=paypal+passkey&ia=web and the first hit was this help article: https://www.paypal.com/us/cshelp/article/what-are-paypal-passkeys-help997 which explains a lot. Note that if PayPal changes the /us/ part of the URL to your local language, it will probably show article not found, at least it did for me when it automatically switched to /se/.

According to the article you have to configure a passkey from a mobile device and you do that during the login process. There's also a paragraph about current platform support.

Which technology providers support Passkeys?

Today passkeys are supported by Safari and Chrome web browsers on Apple devices running iOS 16, iPadOS 16 macOS Ventura, and google devices running Android 9+. Passkeys are not supported on web views and windows devices. On a Windows device, the user will have to use a password or SMS OTP as a way to log in.

Before I found that article, I poked around in my account and found a setting under https://www.paypal.com/myaccount/security/ > 2-step verification > Add a device, where there was a single option called Use a security key. But when I clicked on it, it just says Finding your security key, as it did for tonkku107. Since the "add security key" method isn't mentioned in the article above I'm guessing it's to be used with a physical FIDO key.

There's also https://www.paypal-community.com/t5/Managing-Account/It-s-many-articles-that-PayPal-suport-Passkeys-now-But-how-to/td-p/2999372 in their community forum.