Tested with VS-Desktop-3.2.93.33-Beta:

Tested with VS-Desktop-3.2.93.33-Beta, where everything necessary is backported:

current plan after discussion today is as follows:

works in VS-Desktop-3.2.93.33-Beta

afaik "Valid Until" is actually available for keys coming from WKD

Very good suggestion! +1
I believe Werner and Alexander will agree, too, as we talked about that tab the other day and that showing only the last certification would be preferable

If this is easy to solve and backport, I would like to have this in the next release, as we did a lot of column related changes in other tables already for that release.

Suggestion for the "placeholder" screen:
Only show "Please insert a compatible smartcard." And then below: "Known supported smartcards are listed at https://gnupg.com/kb/smartcards.html".

Did a quick manual test import and encryption/decryption with VS-Desktop-3.2.93.1-Beta with the relevant test-X509 certificate.
Works as expected.

First: we should do something about the placeholder text, too. It is a bit misleading ("But it says Netkey cards work, why doesn't mine?"…)

As there was some discussion in the ticket: what has been implemented? How can it be tested?

to document the answer to my own question: The serial number is unique for the manufacturer, e.g. Yubico. But serial numbers of devices of different manufacturers might have the same serial numbers, although it is unlikely.

with gpg4win-Beta-41:

Status is testing for 2.4, no backport yet for 2.2, so there it stays in the backlog column

checked with Gpg4win-4.3.2-beta41:

We decided how it should be implemented.

as this is a regression, I would like to have a fix in the upcoming release

looks fine, gpg4win-Beta41

Try it. It does not do what you think ;-)
You will revoke the certification of the User-Id and not remove that one certification. I should have taken a better example for the screenshot:

Icon is there in GnuPG-VS-Desktop-3.2.93.32-Beta

tested with Version VS-Desktop-3.2.93.32-Beta

works

done (gpg4win -Beta41)

Looks good, gpg4win-Beta41:

Done, checked with Gpg4win-Beta41

Texts are improved, checked with Gpg4win Beta-41

ok, checked with Beta-41

noticed testing T7128: The Token is very long. Is the serial number not unique? That one is much shorter and therefore better to handle visually

tested with Version 3.2.2.2405000+git~ (Gpg4win-4.3.2-beta41)

Checked in Version 3.2.2.2405000+git~ (Gpg4win-4.3.2-beta41):
Looks ok to me.

This is how the upper part of the "New Group" window looks with Version 3.2.2.2405000+git~ (Gpg4win-4.3.2-beta41):

The basic task is definitively done and looks good.
It is not clear if the improvement wishes commented later have consensus and they should be addressed in an new ticket, anyway.