Show input prompts from LUKS/systemd on Plymouth Boot Screen

[nagmat84]

I have setup Root FS encryption with LUKS. Key slot 1 uses a password, key slot 2 is associated to a FIDO2 stick (Yubikey). Moreover, I have enabled a Plymouth boot screen. The Plymouth boot screen only shows a light gray spinning cog wheel on an otherwise black background. Systemd first waits 15 seconds for the Yubikey to come online and the user to confirm its physical presence. After a timeout of 15secs, systemd asks for the LUKS password. Overall, everything works as expected, but the Plymouth boot screen is a little bit confusing, because it hides the prompts.

In particular, the only hint that the user is supposed to touch the FIDO2 stick is the green flashing light on the FIDO2 stick itself. The textual user prompt "Please confirm presence ..." is hidden behind the Plymouth boot screen.

After the timeout, the Plymouth boot screen indeed shows an "input box" for the password, i.e. there is line of light gray boxes below the spinning cog wheel, but again no prompt. The prompt "Enter LUKS passphrase .." is hidden behind the Plymouth boot screen. If one provides the wrong password, the error message is not shown either.

However, all this messages are visible if the user presses "ESC" and hides the boot screen.

Is there any option to make the Plymouth Boot screen a little bit more verbose? As the Plymouth boot screen is able to show an input box, there obviously is some kind of interaction between LUKS, systemd and the Plymouth boot screen. It would be nice, if the Plymouth boot screen would show the messages as well.