- Edited
It works for me, at least for logging in to Google. Had to install Sandboxed Google Play Services and Chrome (the original).
On my Windows desktop, when I use Chrome to log in to my Google account I'm asked if I want to use a Passkey for login. When I do, I'm presented with a QR-code. I scan that on my Graphene OS Android phone (with a 3rd party app called Binary Eye), follow the link and see the Google-branded "Do you want to use your Passkey" screen. When I confirm, I'm asked to scan my fingerprint. Afterwards, I'm logged in on my desktop browser.
Haven't tried it with other services yet.
I had created the Passkey using the Google Android app previously. But during the process that I describe above, the Google app is deactivated.
When I relogin later, I'm not presented with the QR-code again. I can select the device ("Pixel 7") from a list and a Google Play Services notification pops up on my Graphene OS phone, which takes me to the Fingerprint screen.