Yubikey 5c nano not working on Pixel 3

[jmandel]

When I plug my Yubikey 5c nano into the usbc port of my Pixel 3, OpenKeychain attempts "gathering information" but does not find any keys.

Expected Behavior

I expect to be asked to enter a PIN, thereby unlocking my device... and then I expect OpenKeychain to find and list the keys on it.

Current Behavior

I am never prompted to enter a PIN, and OpenKeychain proceeds to look for keys but fails. Here's a 1 minute narrated screen recording of what I'm seeing:
https://photos.app.goo.gl/vCqhCJApKXWDd9aV8

Steps to Reproduce (for bugs)

1. Launch OpenKeychain 5.2 (or 5.3 beta 3) on Pixel 3
2. Click "USE SECURITY TOKEN"
3. Insert Yubikey 5c nano into usbc port
4. Approve permission request for OpenKeychain to access device

Context

This issue is preventing me from accessing gpg keys on my phone.

Your Environment

• Android Version: 9 (PQ2A.190305.002)
• Device Model: Pixel 3
• OpenKeychain Version: 5.2; 5.3 beta 3
• From Google Play or F-Droid?: Tried both

[jmandel]

Thanks for the suggestion @keithw -- after hosting my key at a public URL and then

$ gpg --card-edit 
> admin
> url

to save the URL on the device... then this worked. But I wasn't expecting to need to perform this step, and I didn't see a prompt to do so. If I missed the docs, my apologies (but perhaps an on-screen prompt or suggestion could help).

[TranceLove]

At my work where SSH access using Yubikey is required, on setup my work environment I'm using programs like gpg --card-edit and pinentry as well. Never in the instructions I read, that I need to put my public key out to the wild - my company would have looked for other solutions if such case exists.

I expect Openchain here is to act simply as a key agent completely offline, when using with hardware tokens like Yubikey, that prompt user for the key and PIN when required, that's all.