I don't mind if this is marked as resolved. As long as I use my script, the agent works flawlessly with my Nitrokey. The agent startup is very fast. The script also resolves the effect that the agent won't work after the system is waked from sleeping state.

While the initial agent hang problem might be rare, it nevertheless does make sense to have a workaround for this in any case. Especially since it may not be possible to patch this effect away. The commands given by Werner provide this workaround nicely if gpg-connect-agent hangs.

These are very nice commands which I had overlooked. My results:

In T4978#135418, @werner wrote:

The 5 second timeout is to give the agent time to get ready and accept connections.